NEWMARKET COURT FILE NO.: CV-08-087238-00

DATE: 20120330

ONTARIO

SUPERIOR COURT OF JUSTICE

BETWEEN:

FELIX CHAN, A MENTALLY INCAPABLE PERSON BY HIS LITIGATION GUARDIAN, MILLIE CHAN, MILLIE CHAN and JULIE HO

Plaintiffs

– and –

DR. HUNG-YIP TANG

Defendant

P. Harte and M. Damiano, for the Plaintiffs

W.D. Black, E.C. Margues and S. D’Souza, for the Defendant

HEARD: November 15, 16, 17, 18, 21, 22 and 23, 2011

REASONS FOR JUDGMENT

MULLIGAN J.

INTRODUCTION

[1] Felix Chan suffered a debilitating stroke in January 2006. The stroke left him with permanent disabilities including an inability to communicate and vision problems. As a result he was unable to continue his employment as a computer analyst. Prior to his stroke Felix Chan had a number of medical issues. His family doctor was Dr. Hung-Yip Tang (“Dr. Tang”). He became a patient in 1989. In 1991 his cardiologist started him on a blood thinner known as Coumadin. As his family doctor Dr. Tang became his primary care physician for the purposes of monitoring and maintaining the amount of Coumadin prescribed to Felix Chan.

[2] There are three issues for trial. First did Dr. Tang breach the standard of care expected of a family physician in prescribing and monitoring Felix Chan’s Coumadin, particularly with respect to the weeks and days immediately preceding the stroke? Second, if there was a breach of standard of care did it cause Felix Chan’s stroke? Third was Felix Chan negligent or contributorily negligent in his role as a patient in the doctor-patient relationship?

[3] The parties have agreed on damages so assessing damages was not an issue for trial.

[4] The plaintiffs allege that Felix Chan’s stroke was caused by the negligence of the defendant, his family physician, Dr. Hung-Yip Tang. He failed to meet the standard of care of a reasonably competent physician and this negligence was the cause of Felix Chan’s stroke. The defendant alleges that Felix Chan’s stroke was an unfortunate outcome; there was no breach of the standard of care. Alternatively the defendants allege that Felix Chan was negligent or contributorily negligent. He was non-compliant with orders from his family physician as part of the doctor-patient relationship. The matter is complicated by the opinions of medical experts who came to different conclusions after reviewing Dr. Tang’s voluminous charts and notes accumulated over 15 years of his care for Felix Chan.

[5] After considering the testimony of the witnesses, the exhibits entered at trial and the submissions of counsel I have concluded that, on a balance of probabilities, the plaintiffs have proven their case against Dr. Tang. For the reasons that follow I conclude that Dr. Tang breached the standard of care of a reasonably competent family physician and this breach was the cause of Felix Chan’s stroke. I also conclude on a balance of probabilities that Felix Chan was not negligent or contributorily negligent within the doctor-patient relationship.

[6] Both parties called a number of medical experts with respect to the issues of standard of care and causation. At the beginning of the trial an Agreed Statement of Facts was filed. A summary of the Agreed Statement of Facts will provide context for the discussion that follows:

(a) The defendant Hung-Yip Tang (“Dr. Tang”) was and is qualified to practice family medicine in Ontario. The plaintiff, Felix Chan (“Mr. Chan”) first saw Dr. Tang in the spring of 1989. Dr. Tang subsequently became Mr. Chan’s primary care physician.

Atrial Fibrillation

(b) In April 1991, Mr. Chan was diagnosed with atrial fibrillation (“AF”), a heart rhythm irregularity.

(c) People with AF usually have a significantly increased risk of stroke. Stroke risk increases during AF because blood may pool and form clots in a poorly contracting chamber of the heart.

(d) People with AF are often given anticoagulants (commonly known as blood thinners) such as Coumadin to protect them from stroke. Coumadin is the brand name of the drug known generically as warfarin.

(e) Mr. Chan was started on Coumadin in 1991 by his cardiologist Dr. James.

Heart Valve Replacement

(f) In January 1994, Mr. Chan underwent a replacement of his aortic and mitral valves to repair damage to his heart valves caused by childhood rheumatic fever. The valves were replaced with mechanical prosthetics. Mechanical valves can cause clot formation. Mechanical heart valves therefore require lifelong treatment with an anticoagulant such as Coumadin.

Coumadin

(g) Mr. Chan had both AF and mechanical heart valves. Both conditions could lead to clot formation and ultimately stroke. Therefore Mr. Chan was prescribed Coumadin, in part to prevent strokes.

(h) Prior to the valve replacement, primary responsibility for monitoring the Coumadin therapy was being handled by Mr. Chan’s cardiologist, Dr. James. After the valve replacement in 1994, Dr. Tang took over responsibility for managing Mr. Chan’s Coumadin therapy.

(i) From on or around January 2001 to on or around January 2006, Dr. Tang was paid between $10.10 to $10.60 a month to oversee Mr. Chan’s Coumadin therapy.

Therapeutic Range

(j) Coumadin must be administered and monitored carefully. Coumadin’s therapeutic range is measured using INR. [International Normalized Ratio]

(k) INR is a standardized method of measuring prothombin time, or the time it takes blood to clot. A normal INR (in a person not taking an anticoagulant) would typically be between 0.8 and 1.3.

(l) The therapeutic target range for a person with prosthetic heart valves, (i.e. Mr. Chan) is an INR between 2.5 and 3.5.

Coumadin Treatment

(m) Throughout the 1990s, Mr. Chan had periodic blood tests to monitor his INR levels. Starting on January 31, 1994, from time to time, Dr. Tang advised Mr. Chan to adjust his dose of Coumadin.

(n) INR results were reported to Dr. Tang on or about the day indicated in the table [filed at trial].

Potential Transient Ischemic Attack (“TIA”)

(o) On January 12, 2006, Mr. Chan reported to Dr. Tang that on December 23, 2005, Mr. Chan experienced an episode in which he had difficulty finding words to express what he wanted to say. The symptoms cleared after a few minutes.

January 12, 2006

(p) Mr. Chan saw Dr. Tang on January 12, 2006 at the request of Dr. Tang after Mr. Chan’s January 9, 2006 INR test result came back at 1.1. At that visit, Mr. Chan said he had been taking his Coumadin regularly at a dose of 1.0 mg daily. At that visit, Mr. Chan also advised Dr. Tang, for the first time, of the confusion/garbled speaking he had experienced a few weeks before.

(q) Dr. Tang suspected that Mr. Chan’s symptoms of December 23, 2005 might be the result of a mini-stroke. Dr. Tang advised Mr. Chan to have his INR tested again immediately and to increase his dose of Coumadin if his INR remained low.

The Stroke

(r) Early on January 14, 2006, Mrs. Chan found her husband unresponsive after she awoke him when he was breathing strangely. Mr. Chan was taken by ambulance to Markham Stouffville Hospital (“MSH”) at 2:00 a.m.

(s) At MSH Mr. Chan showed right sided weakness and aphasia (loss of ability to produce and/or comprehend language). Mr. Chan was admitted to MSH.

(t) On admission Mr. Chan’s INR was 1.3 on a dose of Coumadin reported to be 1.5 mg per daily.

(u) While at MSH, Mr. Chan was diagnosed with embolic stroke, secondary to subtherapeutic anticoagulation, and treated with intravenous anticoagulants.

(v) On the third day following his admission to MSH, Mr. Chan experienced a decreased level of consciousness. A CT scan of the head performed at this time indicated the presence of a large intra cerebral haemorrhage.

(w) Mr. Chan was subsequently transferred to Toronto Western Hospital for further management.

(x) Mr. Chan was 48 years old when he suffered his stroke on or around January 14, 2006.

(y) On January 27, 2006, Mr. Chan was transferred to North York General Hospital, and subsequently admitted to Toronto Rehabilitation Hospital and then to Providence Healthcare for rehabilitation. Mr. Chan was discharged home after 8 months of rehab on September 1, 2006.

(z) As a result of his stroke on January 14, 2006, currently, Mr. Chan has aphasia that affects his capacity to communicate, walks independently but with a limp and has hemiparesis of his upper right extremities and diminished right side peripheral vision in his right eye.

(aa) As a result of his stroke on January 14, 2006, Mr. Chan has been unable to work and will be unable to seek gainful employment for the remainder of his life. Mr. Chan participates in a number of community programs.

[7] Because of his stroke and inability to communicate Felix Chan was unable to testify at trial. However his spouse and litigation guardian, Millie Chan, gave evidence about their life together. In addition the plaintiff called two expert witnesses. The first was Dr. Alan John Drummond. Dr. Drummond is a specialist in family medicine and was qualified to give his opinion as to the standard of care expected of a family physician responsible for the management of patient coagulation therapy. The plaintiff also called as its expert Dr. Richard Mainwaring Upton. Dr. Upton is a neurologist and a professor of medicine (neurology) at McMaster University. He was qualified to give evidence on the issue of causation. The plaintiff called as a witness Mrs. Patricia Clements who is Operations Manager for CML Labs. CML Labs processed many of the blood tests that Felix Chan had taken over the years as a patient of Dr. Tang.

[8] The defence called Dr. Tang as its witness as well as two members of his office staff. In addition the defence called two expert witnesses. Dr. Harvey Blankenstein is a family physician who is an assistant professor at the University of Toronto, Department of Family and Community Medicine. He was qualified as an expert to give opinion evidence on the standard of care expected of a family doctor with respect to the management of a patient’s anticoagulation therapy. The defence also called as its expert Dr. Demetrios Sahlas. Dr. Sahlas is a neurologist currently serving as a professor in the stroke management division of neurology at McMaster University. He is also been involved in physician education about treatment and prevention of strokes. He was qualified to give evidence with respect to the standard of care for family physicians managing Coumadin. In addition he was qualified to give evidence on causation issues relating to stroke. All four experts had an opportunity to review Dr. Tang’s extensive charting of his care of Felix Chan over the years. This review also included a review of the blood test results obtained by Dr. Tang over the years. The experts for the plaintiffs and the defendant disagree as to whether or not Dr. Tang met the reasonable standard of care expected of a competent family physician with respect to the treatment of Mr. Chan. Although Felix Chan’s entire treatment history was reviewed the last several months before his stroke became the focus for the experts at trial as to the standard of care and causation.

[9] In order to understand the evidence of the experts it is important to understand Felix Chan’s medical history, the benefits of Coumadin, and the risks associated with Coumadin for a patient like Felix Chan.

[10] The medical experts were in substantial agreement on the benefits of Coumadin. Coumadin is the brand name of a blood thinner. It’s generic name is Warfarin.

Why Felix Chan needed Coumadin?

[11] It is quite likely that Felix Chan had childhood rheumatic fever. He was born in 1957. By 1991 he was diagnosed with a heart rhythm irregularity known as atrial fibrillation. At that time his cardiologist started him on a dose of Coumadin. In 1994 he had surgery to replace his aortic and mitral valves to repair damage to his heart valves caused by rheumatic fever. Because mechanical valves can cause clot formation, patients require a lifetime treatment with an anticoagulant such as Coumadin.

Why did Felix Chan require an Anticoagulant?

[12] Replacement mechanical heart valves solve a problem with respect to heart function but they create a new potential problem. As Dr. Upton noted in his evidence when the heart starts beating irregularly or if valves have to be changed within the heart then blood tends to clot either on the valves or in the atrium. As Dr. Upton noted in his evidence:

This in the past would lead then to a stroke because the blood clots would fly off from the heart and be pumped into the arteries around the body...many of the blood clots shoot up the vessels to the brain because the brain has such a rich blood supply.

So the modern times, the last 50, 60, 70 years it has been realized that the probability of developing a stroke if one has atrial fibrillation or one has heart valves that have been replaced, can be gravely reduced if the blood is thinned, that is if it is allowed to take longer to clot.

[13] As Dr. Sahlas explained in his testimony blood thinners such as Coumadin can be effective in preventing strokes:

The two conditions [atrial fibrillation and mechanical heart valves] promote the formation of clots within the heart, which then could go up to the brain and cause a stroke. Coumadin, it’s a vitamin K antagonist. Vitamin K is very important in the cascade of clotting factors and so it helps impede the development of clots to begin with. So, it lessens the likelihood that clots will form and hence that strokes will occur.

Risks Associated with Coumadin

[14] All of the experts agree that Coumadin reduces clotting and therefore reduces the risk of stroke if patients are treated with Coumadin. But they were also in agreement that Coumadin is a dangerous drug if not properly prescribed and monitored. As Dr. Drummond said in his evidence:

If you anticoagulate a patient, then they get too much Coumadin then you run the risk of significant bleeding or haemorrhage. If you under-coagulate a patient then you increase the risk of a thromboses or an embolic event.

As Dr. Sahlas said in his evidence “Coumadin does not dissolve away clots. It prevents their formation to begin with and prevents them from growing.”

Prevention Measure

[15] Dr. Sahlas testified that Coumadin can achieve a seventy percent reduction in the risk of stroke for patients expressing symptoms such as those Felix Chan had.

[16] As the first medical expert to testify, Dr. Drummond, defined a stroke as:

The result of deprivation of lack of blood supply to areas of the brain. ...it can be caused by a number of mechanisms; one would be thromboses from clotting of a major blood vessel because of the usual risk factors associated with such things as diabetes, hypertension, hyperlipidemia, smoking. It can be due to a break-off of a clot from a major artery in the neck. It can be what we call a cardioembolic, which is a clot from the heart that goes to the cerebral circulation and deprives the brain of oxygen, and it can be caused by bleeding such as intracerebral bleed where a small blood vessel breaks within in the parenchyma or the substance of the brain causing that of a blood clot within the substance of the brain, or a subarachnoid haemorrhage which is a vessel on the surface of the brain which can cause problems with intracranial pressure.

[17] Dr. Drummond spoke of two kinds of stroke, ischemic strokes which are caused by a blockage and haemorrhagic strokes which are caused by bleeding.

[18] The administration of too little Coumadin fails to provide the patient with the desired protection from the accumulation of a blood clot which might be released into the blood stream. But too much Coumadin can also have a negative effect on patients. As Dr. Sahlas said in his testimony:

If you take too much Coumadin...then the risk of haemorrhagic complications steeply increases and these can be catastrophic, anything from haemorrhaging in the brain to haemorrhaging in the gastro-intestinal tract and so forth. So it’s a very difficult medication to use. Frequent monitoring is required to optimise the amount of time the patient is within the therapeutic range, which is never 100%.

[19] The experts agreed that too little Coumadin could potentially provide a subtherapeutic dose increasing the danger of an ischemic stroke, and too much Coumadin could produce a supratherapeutic dose with the potential for bleeding and a hemorrhagic stroke.

Coumadin Testing and INR

[20] Coumadin in the blood stream is measured by a simple blood test, the results of which lead to a reading called the International Normalized Ratio (“INR”). The amount of Coumadin required will depend on the symptoms of the patient. A patient in the general population without receiving Coumadin would have a reading of about 1.0 INR. Patients without symptoms, such as were present with Felix Chan, are not prescribed Coumadin in the ordinary course because of the substantial risk of bleeding. Once a patient requires anticoagulants the accepted risk of bleeding is balanced against the substantial benefits of the reduction of clotting. The experts agree that in patients such as Felix Chan, presenting with dual symptoms of atrial fibrillation and mechanical heart valves, the target range is 2.5 to 3.5 INR. Within this range an optimal reading would be 3 INR.

How Coumadin is Prescribed?

[21] Coumadin is an oral medication taken in tablet form in accordance with a doctor’s prescription. A patient will often start with a prescription for a 5.0 mg tablet. Thereafter a patient is tested frequently to determine if this dose is too high or too low. In the early days of introducing Coumadin a patient may be tested several times a week and then transitioning to weekly, twice weekly or monthly testing. Monthly testing becomes the norm when the treating physician is satisfied that the prescribed dose, as adjusted, leads to a satisfactory INR reading within the appropriate range for the patient.

Physician Maintenance

[22] Family physicians often maintain a roster of their patients who are receiving Coumadin. Both family physicians who testified as experts indicated that they both maintain a number of patients on Coumadin. OHIP provides monthly compensation to family doctors who maintain such patients. Dr. Drummond identified the OHIP schedule of benefits and confirmed five elements that physicians were required to perform. The five specific elements are:

A. Monitoring the condition of a patient with respect to anticoagulant therapy, including ordering blood tests, interpreting the results and inquiry into possible complications.

B. Adjusting the dosage of the anticoagulant therapy and, where appropriate, prescribing other therapy.

C. Discussion with, and providing advice and information to the patient or patient’s representative(s), by telephone, on matters related to the service even when initiated by the patient or patient’s representative(s).

D. Making arrangements for any related assessments, procedures or therapy and interpreting results as appropriate.

E. Providing premises, equipment, supplies and personnel for the specific elements.

Factors affecting INR

[23] Felix Chan was monitored by his family physician, Dr. Tang, for over 15 years. Based on frequent blood tests over the years Dr. Tang adjusted the dose of Coumadin numerous times. There were times when Felix Chan’s INR was subtherapeutic, or below the acceptable range and his Coumadin dosage was increased. There were times when his INR was above the therapeutic range or supratherapeutic and his dosage was decreased. Felix Chan is of Asian descent and the experts agreed that studies have indicated that persons of Asian descent may be more sensitive to Coumadin. Felix Chan was able to stay in the therapeutic range on a lower dose of Coumadin than many other patients.

[24] The experts also agreed that there are a number of factors which would occur in a patient’s life that would affect his INR result. The introduction of new prescription medications, over the counter medications, dietary changes such as green or leafy vegetables or herbal medications, could all have an effect on a patient’s INR reading. During the course of Dr. Tang’s management of Felix Chan it was noted that Mr. Chan was taking an antiarrhythmic including Amiodarone and an antibiotic. In addition he was taking prescribed lipid lowering medications. Felix Chan also notified Dr. Tang that he was taking herbal medications for a time. When a family physician notes an INR reading that has dropped to the subtherapeutic level or raised to the supratherapeutic level a cause may be attributed to one or more of these factors. The dosage is then monitored and if necessary adjusted and followed up by further testing to determine if the adjustment brings the patient back into the therapeutic range.

[25] Dr. Upton acknowledged that a number of factors alone or in combination including travel, change in diet, environment, physical state or medication or the use of natural medicines may influence a patient’s response to anticoagulants.

Maintaining a patient within the therapeutic range

[26] Given the number of variables that could affect a patient’s INR the experts spoke about the difficulty of maintaining patients within the therapeutic range. When asked why it was not possible to keep a patient within the therapeutic range 100 percent of the time Dr. Blankenstein, a family physician, stated:

Nothing is that perfect. The challenges of Coumadin monitoring and administration is it’s so multi-factorial, Coumadin is such a sensitive medication that drugs, foods can change the metabolism quite dramatically. Alcohol can change the metabolism dramatically. Missing a dose affects the therapeutic range. If somebody becomes ill for instance they may have some vomiting associated with flu like illness they may end up throwing up the medication, so it becomes quite precarious.

As Dr. Sahlas, a neurologist, stated in his evidence:

Frequent monitoring is required to optimize the amount of time the patient is within therapeutic range, which is never 100 percent. At best it’s 60 to 80 percent and those are the vagaries of the medication.

As Dr. Sahlas went on to state about Coumadin:

It’s been viewed as an imperfect therapy for decades and in Ontario if somebody is within the therapeutic range at least 60 percent of the time that is considered about as good as most people are able to get, understanding the difficulties with the management.

[27] Dr. Drummond, a family physician, gave much the same evidence and stated:

We strive to maintain people within that therapeutic range and we try very hard to maintain people within that range but humans being what they are and the circumstances of life, no it’s not possible to be 100 percent effective…after 100 percent effective…I think if you embrace the concepts of – of care then it’s possible to be in the 70-75 even 80 percent range depending on the circumstance.

Dr. Drummond went on to say that as a family physician, once the patient has been established in a steady state, it is a matter of maintaining the patient within the therapeutic range. As he stated:

We need to know when to adjust the dose and we need also to know how to adjust that dose to make sure that we don’t overshoot or undershoot in our treatment.

[28] In speaking of the strategy of maintaining a patient Dr. Blankenstein stated:

I don’t think there’s any right strategy in this situation. I think there is where the art of medicine is and you have to take all the compounding variables and the fact that he was on a medication that does affect the Coumadin, the Coumadin dose and you have to adjust accordingly.

[29] The medical experts agreed that when a patient presents an INR reading that is below or above the target range the family physician has some choices to make. The doctor can modify the dose and retest to see if that achieves the necessary result or the doctor can elect not to change the dose but retest. This would give the doctor an opportunity to see if any possible underlying factors in the patient’s life such as a temporary illness, once resolved, would allow the INR reading to return to the therapeutic level without dosage adjustment.

Doctor-Patient Relationship

[30] It is clear from the evidence of the medical experts that in an effective use of Coumadin therapy much depends on the strength of the doctor-patient relationship. The patient is required to take the medication and have regular blood tests as required. The doctor is required to establish the required maintenance dose of Coumadin so that the patient is within the therapeutic range. This is accomplished by an initial prescription and an adjustment of the dosage when the results of regular and frequent INR tests are received. There is an education component required as well. A patient, well-educated by his physician about Coumadin, is more likely to inform his doctor if there are changes in his medication, dietary changes, temporary illnesses or the use of alternative medications. Once tested the patient needs to be in touch with his or her physician’s office to determine whether or not the INR is within range and if not what steps need to be taken if any to bring the reading within the appropriate range.

[31] Dr. Drummond spoke as a family physician about the importance of this partnership. As he stated in his evidence:

I think long-term coagulation therapy requires a partnership. I mean, you’re doing this for the benefit of the patient so there has to be a little give and take with respect to monitoring but at the end of the day a physician is just responsible for the care that he provides, if you’re providing anticoagulation then I think you need to insist on a reasonable degree of compliance with monitoring.

Dr. Drummond went on to indicate the importance of patient education and stated:

We will usually initiate some counselling session at some point and initiation of the patient’s long-term coagulation therapy.

Dr. Blankenstein spoke as a family physician about the doctor and patient relationship. As he stated:

There is dual responsibility. I think the doctor and the patient have to come to a mutual understanding of all the factors and influences in monitoring the medication, that being the frequency of monitoring, how they’re going to follow up on lab results, prescription renewals, backup in terms of following up on results and a sense of urgency on following up on those results, having a fulsome discussion about the interactions of various medications, foods that interact with the medications, and illnesses that may influence the administration of medication, and the ability to go and get tests done. So there’s a lot to be discussed and there should come to a mutual understanding of who is doing which part and that there’s a mutual responsibility.

How Family Physicians Maintain Coumadin Patients

[32] Both the plaintiff and the defendant called family physicians to give expert evidence as to the standard of care. The plaintiffs’ expert, Dr. Alan Drummond, spoke about how he approached the task with respect to his Coumadin patients. He cares for about 1800 patients and has about 44 patients currently on Coumadin. When asked to explain his system within his office he indicated:

I have a system and I think we all have a way of doing it. I don’t think anything is particularly cast in stone. It depends on the individual’s position but what you want to do is make sure that the patient doesn’t fall through the cracks and either overshoots or undershoots. So in my particular practice we do have a list of our Coumadin patients and I know we have that list because my office manager bills monthly for Coumadin monitoring of the patient.

We also get a written copy of the patient’s INR when they report to the lab. That report is seen by me and the patient’s chart is pulled. I have a written chart although I’m moving to an electronic record but the patient’s chart is pulled. On that chart is a flow sheet by which I know when the patient’s last INR was taken, what the INR result was the last time, what their dosage was, and then I action to my staff to either call the patient to say things are fine or there is a deviancy I’m concerned about, and we need to address that. All of my patients are instructed to call my office the day after they’ve had INR so we can touch base even though at the end of the day I’ll be the one responsible and will be calling them if there’s any area of concern.

[33] Dr. Drummond spoke about the importance of the partnership between doctor and patient in monitoring long-term anticoagulation therapy. He spoke of it as a partnership and stated:

A physician is just responsible for the care that he provides, if you’re providing anticoagulation then I think you need to insist on a reasonable degree of compliance with monitoring.

When asked what he would do if the patient stopped regular monitoring he indicated he would call the patient in for a discussion, indicate the potential negative outcomes and the need to document in the chart aspects of patient education and counselling.

[34] About his system he was asked: “if a patient doesn’t come in for testing is that something that your system would pick up?” He answered:

It would and also I limit the – another mechanism to improve compliance is I limit Coumadin prescriptions to three months so that if you – god forbid somebody should sneak through the system, I know they’re going to run out of Coumadin within that three month timeframe and are going to have to see me and then at that time we will review what’s happened, “why have you not been coming in, you need to come in this is a – this could be dangerous”.

[35] Dr. Drummond went on to indicate that his office manager who bills the monthly fee to OHIP would be aware of who is received an INR within that month’s timeframe.

[36] Dr. Harvey Blankenstein gave expert evidence for the defence as a family physician. Dr. Blankenstein indicated that he currently supervises about 25 to 30 patients on anticoagulation therapy. Dr. Blankenstein currently has about 1300 rostered patients and another 200 non-rostered patients. Dr. Blankenstein also talked about the dual responsibility between the doctor and the patient. As he explained the practice in his office:

In my practice I try to ensure that we have an equal understanding of everyone’s role. I typically call patients with their INR results. As a backup I’ll tell patients that if you don’t hear from me call by the end of the day or the next day that I’ll be giving you a requisition form. My understanding is that you’ll follow directions and – do the blood work as directed, as advised, taking into account that patients make an informed decision on what they want to do.

Q: Why is the onus on the patient in that setting to follow the advice and directions that you’ve given?

A: Again it’s multi-factorial. Patients have different belief systems, different influences, different obligations – responsibilities at home, it may become difficult for them to meet these directions. They have to assume some sort of responsibility for their care and demonstrate that they understand the immediacy or urgency of the situation.

[37] When asked if he would note that a patient was failing to attend for weekly INR monitoring Dr. Blankenstein replied:

I wouldn’t expect that. In fact I don’t have a system in my office either that I know of patients where - compliant with the frequency of monitoring them.

[38] When asked about charting notes Dr. Blankenstein indicated that he was able to complete this charting about 50 percent of the time during the patient visit but acknowledged that there were times that he would do the charting after the patient visit. Occasionally he might chart a week later. He acknowledged the standards of the College of Physicians and Surgeons of Ontario, as entered as an exhibit, which provided the following advice to physicians:

You should record entries as closely as possible to the time of examination when details of the patient encounter are fresh in your mind.

INR Testing

[39] Felix Chan was first introduced to Coumadin by his cardiologist Dr. James. In 1994 Dr. Tang took over responsibility for managing the Coumadin therapy. It was not disputed that the target range for a therapeutic level of Coumadin for Felix Chan was an INR reading of 2.5 to 3.5 with a target of 3.0. From February 1994 to January 2006 Felix Chan had over 200 INR tests. These tests were generally conducted at a lab. Mr. Chan would take in a requisition, often authorizing tests for a six month period, and blood would be drawn for testing. The lab would send the test result to Dr. Tang’s office by courier and it would be received either later the same day or the next day. On occasion the lab would also fax the result directly to the doctor’s office.

[40] The first INR reading recorded in February 1994 was 5.7 on a dose of 5.0 mg. There followed a frequent series of INR tests indicating lowering INR results as the dosage was lowered. By March 11, 1994 Felix Chan had an INR of 3.0 which was the target for a person with his condition. In the weeks and months that followed there were numerous INR tests taken from that date until July 16, 1999 when Mr. Chan’s reading was 3.4, still within the target range. During this period of time, generally speaking, Felix Chan was within the target range. There were some incidents where his reading was above or below the range but not on a continual basis. As all of the experts agreed it is not possible to keep a patient within the range 100 percent of the time. There are a number of variables that can affect an INR reading such as lab error, change in diet, illness or changes in other medications.

[41] On September 3, 1999 Felix Chan had an INR reading of 6.5 while on a dosage of 2.5 mg. According to all of the experts this reading indicated that the Coumadin dose was supratherapeutic and could lead to bleeding. The dosage was reduced to 1.25 mg. On September 8, 1999 Felix Chan’s INR reading dropped to 1.0. On July 7, 2000 his INR reading was 2.0, still below the therapeutic level. Almost every reading from September 8, 1999 to June 2, 2000 showed INR readings below the target range or at a subtherapeutic level. On July 12, 2000 his dosage was increased to 2.0 mg. On August 15, 2000 Felix Chan’s INR reading was 3.6. Subsequent INR tests from that period until April 30, 2002 indicated that Felix Chan was, generally speaking, within the therapeutic range.

[42] On May 9, 2002 his INR was 2.2 after a recent dosage reduction to 1.0 mg. There followed a series of subtherapeutic readings for the rest of the year until December 11, 2002 when his reading was still at a subtherapeutic level of 1.4 INR. Throughout this entire period Felix Chan was showing INR results which were subtherapeutic while on a dosage of 1.0 mg.

[43] On January 9, 2003 Felix Chan’s INR reading was 4.3 on a dosage of 2.0 mg. However by January 23, 2003 his reading was 2.5 INR on a dosage of 1.5 mg. Thereafter for the balance of 2003 and 2004 his readings generally were within the therapeutic range while on a constant dosage of 1.5 mg. On January 25, 2005 his reading was 2.7 INR which was still within the therapeutic range for Felix Chan.

[44] Felix Chan’s readings in 2005 bear close scrutiny because they preceded the stroke which he had at the beginning of 2006. It should be noted that in 2005 he went for testing less frequently than in the preceding years. In 2005 he had five tests taken. But in the prior years he was tested more frequently. In 2003 he had eleven tests and 2004 he had ten tests. The specific dates and readings for his tests in 2005 are as follows:

Date	INR Reading
25-Jan-05	2.7
03-Mar-05	2.1
10-May-05	2.6
20-Oct-05	4.5
10-Dec-05	1.4

[45] The December 10, 2005 reading was 1.4 INR which was a subtherapeutic level. Felix Chan had three tests in January which were all subtherapeutic. A test taken on January 9, 2006 indicated an INR of 1.1. A test taken on January 12, 2006 indicated an INR of 1.2 and a test on January 14, 2006, after Mr. Chan was admitted to the hospital with a stroke, indicated a reading of 1.3 INR.

The Use of INR Results

[46] Based on the INR results transmitted to Dr. Tang’s office, Dr. Tang had three choices to make about the Coumadin dose each time he received the result. He could increase the dosage if the INR reading was too low, he could decrease the dosage if the INR reading was too high or he could make no change in either case and monitor the reading after a further test to see if adjustments had to be made. In addition Dr. Tang always had the option of increasing testing frequency. After a period of very frequent testing at the beginning of Dr. Tang’s monitoring of Coumadin a pattern of monthly testing settled in and as indicated Mr. Chan had eleven tests in 2003 and ten tests in 2004. The experts agreed that a testing regime of every four to six weeks was adequate for a patient who was on a maintenance dose of Coumadin with results generally falling within the therapeutic range.

[47] Dr. Tang reviewed his clinical notes and records and relied on those notes and records in providing his testimony at trial. He had no contemporaneous memory of specific dealings with Felix Chan. His clinical notes and records recorded the INR readings, discussions he had with Mr. Chan and the changes to prescription when required from time to time. He indicated that he did not always complete his clinical notes and records contemporaneously and sometimes completed them later in the day or later in the week. He blocked off Tuesday mornings to finish notes and charts and acknowledged that there were times when he may have been up to a week behind in charting patient notes.

[48] In forming their opinion on the standard of care the medical experts for the plaintiff and defendant also reviewed Dr. Tang’s notes and charts.

DR. TANG’S EVIDENCE

[49] Dr. Tang is a family physician who was licensed in 1982 and has been practicing in the same location since 1984. He indicated to the court that he has about 2,000 patients and he often sees 20 to 35 people per day. He is supported by office staff. He estimates he has had 100 patients on Coumadin over the years and would typically have 15 to 20 Coumadin patients at any one time in his practice. Dr. Tang works six days a week and indicated to the court that he does not take vacations other than taking Sundays off. Dr. Tang told the court that he only completes charting of patients at the visit about 20 percent of the time. Otherwise he would do the charting later on in the day or the week. He always sets aside Tuesday mornings as his charting day. As far as the doctor-patient relationship, he said that his policy was to instruct patients to call in to get their test results after they had an INR test. He had no independent recollection of dealing with Felix Chan and relied on his charts to assist him in evidence. With respect to requisitions for tests his practice was not to date requisitions so that the patient could use it any time. He did not keep copies in the file.

[50] In examination in chief he indicated that the patient was required to phone in to get tests results and his notation on the INR: “file”, was an indication to his staff that they should get the patient in because a change in dose might be needed. He indicated that it was up to the patient to monitor when a prescription was running out and needed refilling. Dr. Tang reviewed in his evidence the charting notes he made with respect to the various visits of Felix Chan. His recollection of the charting note of November 7, 2005, which showed the high INR reading of 4.5 from the October 20, 2005 test, caused him to decrease the dosage from 1.5 to 1.0 mg. His note indicates to him that he told the patient to get INR checked in a week. An INR test from a blood sample taken on December 9, 2005 showed an INR of 1.4. Dr. Tang’s note indicated “too low needs [increase] dosage.” The note did not indicate the new dosage prescribed nor did it indicate that Felix Chan should be phoned. Dr. Tang reviewed his chart of Mr. Chan’s visit of January 12, 2006 where a possible TIA event was discussed. Dr. Tang told the court he ruled out referring to a neurologist because he thought that the patient wouldn’t be able to see a neurologist for about a month. When he got the reading on January 13 of an INR of 1.2 his plan was to increase the dose. However when his staff called Mrs. Chan they learned that Felix Chan had had a stroke early in the morning of Saturday, January 14, 2006.

[51] After following Felix Chan for 15 years Dr. Tang’s medical records and charts ran to several hundred pages. His evidence was that on his visits with Mr. Chan he would review the current INR test result and flip back through his charts to observe recent tests. He did not review the entire charts nor did he keep a summary or graph of the results of the tests over the years. Had he done so it may have assisted him in determining the appropriate dosage change that would be the most effective for Felix Chan.

[52] Nor did Dr. Tang have a system in place to bring to his attention the fact that a patient was not obtaining regular INR tests.

[53] However I am satisfied that while these issues may represent best practices within the practice of a family physician they do not necessarily reflect the standard of care for family physicians monitoring Coumadin in 2005.

[54] In cross-examination Dr. Tang was questioned about whether he contacted Felix Chan as a result of the December 9, 2005 test result showing a subtherapeutic level of 1.4 INR. The doctor acknowledged that there was no note made in the file about his instructions to make a call or that his secretary had called Felix Chan. Dr. Tang told the court that Felix Chan had a habit of not phoning in to get his test results after INR tests. The doctor acknowledged that on the INR report of December 10 he noted that the dose was low and needed to be increased. Dr. Tang could not point to anything in the chart indicating that Felix Chan had been told about increasing the dose. In addition there was nothing noted on the chart to indicate what the increase in dose should be.

[55] Dr. Tang reviewed his note of Thursday, January 12, 2006. Felix Chan came into the office to review his subtherapeutic INR reading from Monday of that week. There is nothing in the note to indicate that Dr. Tang requested an increase in dosage. The next step was to take another INR test that same day at Dr. Tang’s office. It was Dr. Tang’s view that he needed to take stock. Felix Chan was on a dose of 1.0 mg and had been since his visit of November 7, 2005.

[56] Dr. Tang acknowledged that he had no system in place to call a patient if the patient missed an INR test. He relied on the patient to get the testing as ordered. The results of the test when received at his office provided him an opportunity to review the test and determine whether Felix Chan should maintain the course or have an adjustment to his dose. Because Dr. Tang did not have a system in place to contact a patient who was missing tests it was not apparent to him that INR tests were not coming in for that patient. It was his evidence that the patient had to do his part.

[57] On October 11, 2005 Dr. Tang saw Felix Chan following a prolonged period where there was no testing. The last previous test was May 10, 2005. The doctor reviewed his note which said “advised should get INR weekly!!” The visit of October 11, 2005 was a Tuesday. Dr. Tang admitted that he may have done his charting several days later if not done right away. In fact Felix Chan did get a test about one week later on October 20, 2005. Dr. Tang was referred to Felix Chan’s wallet card which indicated monthly INR testing was authorized.

[58] As a result of the test conducted one week later on October 20, 2005 Felix Chan showed an INR reading in the supratherapeutic level at 4.5. At his next appointment with Dr. Chan on November 7, 2005 this reading was noted in the chart as well as the advice to reduce the dose by half and then recheck, 1.0 mg daily. This chart note does not indicate the requirement for weekly testing.

[59] About one month later on December 10, 2005 Felix Chan had another INR test showing a reading of 1.4 INR. No office visit followed this test although Dr. Tang noted on the test “too low needs [increase] dosage”. The note does not indicate what the increased dosage should be nor does it indicate that this reading, or any increase dosage advice, was passed on to the patient. The lab reports from the previous report and the next following report indicated notes about calling Mr. Chan. This lab note did not.

[60] Felix Chan’s next visit was on the January 12, 2006. This followed Felix Chan’s INR test on January 9 of 1.1. That test was taken almost one month after his last testing date of December 9, 2005 and immediately upon his return from his vacation over Christmas time to Paris. The lab note from the sample of January 9, 2006 indicates Dr. Tang’s instructions “phone him to come in” and also the question noted by Dr. Tang “not taking his Coumadin??” Dr. Tang acknowledges that he did not increase the dosage on this date although the INR test continued to show that Felix Chan’s INR was at a subtherapeutic level.

[61] When asked a question about whether or not he abandoned the patient Dr. Tang’s answer was that “he abandoned me”.

Dr. Tang’s Care

[62] Dr. Tang managed Felix Chan and his Coumadin therapy over a 15 year period. There were prolonged periods where the INR testing indicated that Felix Chan was within the target range given his symptoms. The dose of Coumadin was effective in achieving the result required. However, before examining in detail the months before his stroke there are two earlier periods that require scrutiny.

The First Period

[63] A September 3, 1999 test indicated that Felix Chan’s INR spiked up to 6.5, well above the therapeutic level. Thereafter for a period of several months until July 2000 his INR reading was generally below the therapeutic level. Three successive tests in April, May and June of 2000 all indicated an INR level below the target range.

[64] In August 1999 Felix Chan started to take Lipidil. The experts agreed that the introduction of prescription drugs can have the effect of increasing or decreasing the INR level. Felix Chan’s next INR reading was 6.5 on September 3, 1999. On his next visit to Dr. Tang’s office his Coumadin dose was decreased by 50 percent to 1.25 mg. Tests from April 2000 to July 2000 continued to show INR’s in the subtherapeutic range. On July 12, 2000 Felix Chan attended Dr. Tang’s office and his Coumadin dose was increased to 2.0 mg, an increase of 66 percent. This change had the effect of bringing Felix Chan’s INR readings within the therapeutic range, with few exceptions, until May of 2002.

[65] There was no evidence that this prolonged period in the subtherapeutic level contributed in any way to the stroke that Felix Chan suffered in 2006. However the plaintiff’s expert, family physician Dr. Drummond, opined that this was an example of substandard care. The Coumadin dose was decreased too radically and it was not adjusted upward for many months. This left Felix Chan exposed to the risk of a stroke throughout this period of time.

[66] Dr. Sahlas, the defendant’s expert, a neurologist and an expert on stroke treatments opined in his report that Dr. Tang met the standard of care of a reasonably competent general physician in treating Felix Chan. However, when cross-examined about this period he was more guarded. He acknowledged that Dr. Tang did not exceed the standard of care during this period. As he said later in his testimony:

There are periods where a doctor makes in retrospect the wrong decision and he knows that because the levels are low, that’s what guides his future decision making.

He was later asked:

Q: Family physicians have mentees. If a mentee called you up during this period of time, what would you tell the mentee to do?

A: I’d tell him to increase the dose, for sure. I think it was too long of span.

Q: And so that’s not an example of where of Dr. Tang exceeded the standard of care?

A: That’s not an example no.

[67] Dr. Sahlas acknowledged that he did not draw this period of treatment to the court’s attention in his report. He answered:

A: My intent was that overall, taken as a whole, his care exceeded the standard of care. If you take a look at specific examples where he may have done something different, well then I have to answer you honestly, you know, most physicians would have done something earlier there.

The Next Period

[68] After a prolonged period, generally within the therapeutic, range Felix Chan received an INR reading on April 30, 2002 of 4.4. On his next visit to Dr. Tang’s office his Coumadin dose was decreased to 1.0 mg from the previous dosage which was 2.0 mg. Eleven subsequent INR tests for the balance of 2002 showed Felix Chan was continuously at a subtherapeutic level. On December 11, 2002 Felix Chan attended Dr. Tang’s office and his Coumadin dose was increased to 2.0 mg, a 50 percent increase from the previous 1.0 mg dose. That dose was adjusted downward to 1.5 mg in January 2003 leading to a prolonged period of low INR readings. With respect to this prolonged period of low readings in 2002 Dr. Drummond once again expressed the opinion that Dr. Tang was offering care that was below the standard of care expected of a family physician. As Dr. Drummond stated in his evidence:

Well again this patient is considered to be a high risk patient from a thromboembolic perspective, both from the perspective of atrial fibrillation as well as two mechanical valves of which one was the mitral which was a higher risk associated. You need to keep them in the therapeutic window of 2.5 to 3.5 and anything beyond that for an extended period of time puts this patient at risk.

[69] Once again there was no suggestion in Dr. Drummond’s evidence that this period of substandard care caused the stroke that Felix Chan suffered in 2006.

[70] However it is worth noting that throughout this entire period of time from May to December 2002 Felix Chan was not on an effective dose of Coumadin. He was on a dose of 1.0 mg and obtained eleven blood tests which all indicated an INR below the therapeutic range.

[71] Dr. Sahlas also commented on this period. When asked whether a dose of 1.25 mg would have been more reasonable he said:

In retrospect that would appear to have been a better decision but I don’t think Dr. Tang had the benefit of looking backwards every time to determine what the better dose would have been…I acknowledge that he could have done better in these two periods.

[72] However, Dr. Sahlas’ evidence overall with respect to these two incidents was:

This is something that we’re always dealing with and so, really he did not behave differently than most family doctors would.

THE EVENTS LEADING UP TO FELIX CHAN’S STROKE IN JANUARY 2006

[73] In order to determine whether Dr. Tang met the standard of care of a reasonably competent family physician the events leading up to the stroke must be examined. This includes the INR testing that was conducted through the 2005 period and the evidence of Dr. Tang. Because he did not have any recollection of specific office visits with Felix Chan, his evidence was based on his review of charting notes made during or after visits with his patient, as well as some notes he made on various INR lab reports transmitted to his office. The experts also reviewed the charting notes and INR results to offer an opinion as to whether Dr. Tang met the standard of care of a reasonably competent family physician throughout this period.

[74] Because of his stroke Felix Chan was not able to give evidence at trial. However one of the exhibits entered into a trial was his lab INR authorization card. This is the card which he presented at the lab when he went in for INR tests. The card contained his pertinent identification information and for frequency indicated “monthly”. A barcode was affixed to this wallet card and the date superimposed showed October 20, 2005. The card indicated an expiry date of 2006. The presence of whiteout and an over-stroke from 2005 to 2006 indicated that this card may have been used for some time and updated.

[75] During the trial an issue arose as to whether Felix Chan may have run out of pills by the end of December or the beginning of January of 2006. Pharmacy records were introduced from several pharmacies and Mrs. Chan introduced into evidence a pill bottle which she found at home dated May 10, 2004. The pharmacy records show that Felix Chan did obtain renewals in 2005.

[76] The plaintiff raised an objection to this line of questioning because the issue of running out of pills had not been previously raised. The plaintiffs were able to access much of Felix Chan’s pharmacy records but were unable to obtain a full copy of any records he may have submitted to his employer’s health insurer due to the passage of time from the date of the stroke to the date of trial.

[77] On all the evidence I am not satisfied that Felix Chan ran out of Coumadin pills. First the evidence of all of the experts indicated that Felix Chan was a well educated patient with respect to his need for Coumadin. Second his wife gave evidenced that she observed him taking pills at dinner time. Although she could not be specific about which pills he was taking or not taking she gave evidence about how careful they were about taking pills when they travelled together. Once or twice a year they took extended trips. Felix Chan would take a set of pills with him and give his wife a second set of pills to travel with her. In the event that one of them lost their luggage a second set of pills would be available while he was travelling. In December 2005 they took a trip to Paris. There was no evidence that their invariable practice of taking two sets of pills was changed for this trip. Logic indicates that after the return of this two week trip on January 9, 2006 Felix Chan would still have a supply of pills if he took twice as much with him. Third, Felix Chan had been taking Coumadin for 15 years. There was no evidence that he waited until he ran out of pills to refill a prescription. A pure mathematical count of pills and dates from the last refill does not make any allowance for any pills on hand that Felix Chan may have accumulated over this 15 year period. Further, over a 15 year period of testing and visits with Dr. Tang, there was no history of precipitous INR result drops which were noted in Dr. Tang’s chart as a consequence of not taking Coumadin.

January 24, 2005 Test

[78] Felix Chan had a test on January 25, 2005 at the lab. The INR reading was 2.7 which was within the therapeutic range. He was on a dose of 1.5 mg of Coumadin, a dosage which he had been on for a considerable period of time. Dr. Tang noted on the INR test “same dose o.k.”

March 3. 2005 Test

[79] Felix Chan had a test taken at his lab as requisitioned by his cardiologist Dr. James. The INR reading was 2.1 which was slightly below the therapeutic range of 2.5 to 3.5. On March 16, 2005 Dr. Tang made a note in his chart that Dr. James had added Monocor and noted that Dr. James suggested adding Lipitor.

May 9, 2005 Test

[80] Felix Chan had a test done at his lab on May 9, 2005 which showed an INR of 2.6. Dr. Tang’s note on the INR test was “o.k. same dose”.

Office Visit October 11, 2005 and October 20, 2005 Test

[81] Felix Chan’s next test was not until October 20, 2005. It was over five months after his last test. The reading was 4.5 INR. This reading was in the supratherapeutic range and above the therapeutic range of 2.5 to 3.5 INR. Prior to this test Felix Chan saw Dr. Tang on October 11, 2005. No current INR test was available for the October 11 visit. On his chart Dr. Tang noted that Mr. Chan was on Coumadin 1.5 mg and added to his note “advised should get INR weekly!!”. The October 20, 2005 test that followed was therefore about nine days after Felix Chan’s visit of October 11, 2005. On the INR test from October 20, 2005 the following notes were recorded “left message for him to call us October 20/05”. The note further stated “one-half his dose” and in different handwriting “too high [reduce] dose then recheck one week”. Checkmarks were placed over both of these messages.

[82] It is logical to assume that a message was left with Felix Chan to arrange an appointment because he came to see Dr. Tang on November 7, 2005. Mrs. Chan gave evidence about phone messages received at their home from Dr. Tang’s office over the course of Felix Chan’s care. She generally did not attend at the doctor’s office with her husband; however, it was her policy to check telephone messages at the end of the day when they both arrived home from work. If messages were left from the doctor’s office she would pass that information on to her husband. It was her evidence that the doctor’s office may have reached Felix Chan at work from time to time. I accept her evidence that none of the messages that she received from Dr. Tang’s office contained any advice about increasing or reducing dosages of Coumadin. The messages simply requested that her husband call Dr. Tang.

[83] A review of Dr. Tang’s chart in cross-examination indicates that almost invariably when dosages were to be changed he would have his staff call Mr. Chan to make an appointment to see him in the office. On those visits the INR reading was reviewed and the dosage was changed accordingly. A review of Dr. Tang’s copies of the INR lab results indicates that there were several occasions where he instructed his staff to phone Mr. Chan.

Date	Note on INR Result
INR Report 94/09/01	"Phone him to lower dosage to 3 mg"
INR Report 97/04/16	"Left message for him to call later. Phone him"
20-September-99	"Coming in Tuesday, September 7"
05-Mar-02	"Phone him needs less pills"
09-Jan-03	"Tell him to come in and see me. Left message"
20-October-05	"Left message for him to call us"
09-Jan-06	"Called and left message for him to come in for appoint Thurs or Friday"

Office Visit November 7, 2005

[84] After Felix Chan’s INR test of October 20, 2005 showed a supratherapeutic reading he visited Dr. Tang’s office on November 7, 2005. Dr. Tang noted prescription refills for Lipitor and Lipidil and circled on his note an INR reading of 4.5. Beside that he entered a note “dose one-half then recheck” with an arrow pointing to 1.0 mg daily. The notation did not specify whether the next test should be weekly or, monthly in accordance with the wallet card that Felix Chan had in his possession at the time of the stroke.

[85] Based on one test of 4.5 INR Dr. Tang reduced his dose to 1.0 mg. This was not the first time in the several preceding years that Mr. Chan’s INR had spiked up to an INR of 4.0 or greater. For example a test on March 5, 2002 showed a reading of 4.1 INR. However no dosage change occurred and the INR readings that followed fell back into the therapeutic range. An INR reading on April 30, 2002 was 4.4. After this result Dr. Tang decreased the Coumadin dose to 1.0 mg which was the first time that Mr. Chan had been on this low of a dose. For a considerable period of time prior to this he was on a dose of 2.0 mg. As previously noted this dose reduction to 1.0 mg placed Felix Chan in a subtherapeutic level and was not effective. This dose continued from May to December 2002 when the dose was increased to 2.0 mg in December 2002 and then decreased to 1.5 mg in January 2003. Mr. Chan remained stable on a dose of 1.5 mg for many months that followed until his dose was changed on the November 7, 2005 visit.

December 9, 2005 Test

[86] On December 9, 2005 about one month after this last doctor’s visit Felix Chan’s INR test showed 1.4 INR. This was a reading that was below the target range for Felix Chan and a reading which offered him little or no Coumadin protection against the risk of an ischemic stroke. Dr. Tang made the following notation on his copy of the lab report showing 1.4 INR “too low needs [increase] dosage”. Significantly there was no note on this file that Felix Chan was informed of this reading. The previous INR report from October 20, 2005 had a notation from Dr. Tang’s office indicating “left message for him to call us”. There was no such notation on this lab report. Nor did the note indicate what the increased dose should be.

[87] In previous visits Dr. Tang had spent some time educating Felix Chan on the benefits of Coumadin and the risk of a stroke. It was his expectation that patients would call his office after an INR test to obtain the result of that test. His overall impression was that Felix Chan was not good about calling in for the results. However it should be noted that Dr. Tang directed his staff to call Felix Chan to come in for an appointment after Dr. Tang reviewed his October 20, 2005 test. In addition Mrs. Chan’s evidence was that there were several occasions when she received a message from the doctor’s office that her husband should call.

[88] Based on the December 9, 2005 INR charting of 1.4, I am satisfied that Dr. Tang recognized the need to increase Felix Chan’s dose. The previous reduction in his dose to 1.0 mg had the same effect as the May 2, 2002 reduction to 1.0 mg, that is an INR reading that dropped to a subtherapeutic level. However there is no evidence that this recognition that the dose should be increased was conveyed to Felix Chan. There was no notation on the INR result to indicate that he had been called at work or that a message had been left at his home. There was no notation as to the new dosage. The invariable practice of seeing Felix Chan when dosage was being adjusted was not followed because his next appointment was not until January 12, 2006 and that office visit was as a result of a test January 9, 2006 and a call to him to schedule an appointment.

[89] Not only was there no notation about contacting Mr. Chan there was no notation as to what his proper dosage should be. Was it to be 1.25 mg, 1.50 mg, or 2.0 mg? These were all various dosages that Mr. Chan had been on previously. As a general rule Mr. Chan had attended at the office for dosage changes and those dosage changes were recorded in Dr. Tang’s notes. There was no such record after Dr. Tang reviewed the December 9, 2005 test and no appointment followed Dr. Tang’s receipt of this lab test.

[90] Dr. Tang acknowledged in cross-examination that he could not tell from his chart whether or not a call had been made to Mr. Chan and that there was no notation about a phone call. One of the defence witnesses was Colleen Juhasz who is currently an office manager for Dr. Tang. Between 2001 and 2006 she was a part-time receptionist at the doctor’s office. She indicated that generally patients would call into the office the next day to get their INR results. If not the patient would be called by a staff person. She indicated that the policy was that an INR report would not be filed until the patient had been contacted. She noted that there was a message on the October 20 INR result “left message for him to call us” but could not identify a similar message on the December 9, 2005 INR result.

I am satisfied on all the evidence that Felix Chan was not called about his December 9, 2005 INR result and was not directed by Dr. Tang to increase his dose.

An INR Graph

[91] Dr. Tang retained INR lab results in the chart but did not have a graph or flowchart to show the accumulated results over time. As part of the plaintiff’s demonstrative evidence a number of charts and graphs were introduced as exhibits. The agreed statement of facts contained a list of the approximately 200 INR tests that Felix Chan had over a 15 year period. In order to inform himself Dr. Tang’s methodology was to flip back through his chart to look at several of the most recent INR results. He had no method to immediately scan the results over the years. The experts were asked about such a system and a sample chart introduced for British Columbia doctors in 2010 was shown to the experts. Although the experts agreed that a chart may be of some assistance it was not the standard of care because there are so many variables at work when a patient is on Coumadin. Changes in medication, diet, herbal medicines and other factors can have an effect on the INR reading.

[92] I am satisfied that the lack of a chart or graph showing all of the INR readings did not fall below the standard of care required for a family physician managing Coumadin patients in 2005. However it is possible that if Dr. Tang had looked at how he proceeded on previous occasions when INR readings spiked up then he may have taken a more conservative approach when he changed the dose from 1.5 mg to 1.0 mg after he reviewed the October 20, 2005 INR report. The chart demonstrated that a dose of 1.0 mg had never been an effective dose for Felix Chan.

January 9, 2006 Test

[93] Felix Chan next had his INR tested on Monday, January 9, 2006 approximately one month after his last test. The INR reading was 1.1 and continued to be in a subtherapeutic level. The test from a month previously showed a low reading of 1.4 INR. This test had a date stamp at the bottom indicating “received January 10, 2006”. Notes indicated: “not taking his Coumadin? Phone him to come in”. It also contained the following notes: “January 10/06 called and left message for him to come in for appoint Thurs or Friday”. Felix Chan had an appointment with Dr. Tang on Thursday, January 12, 2006. Dr. Tang’s chart on that occasion noted as follows:

1. SL. Sore throat – one two days

Dry feeling zero fever

2. INR 1.4 has been taking meds regularly 1.0 mg daily no other meds

3. December 23, 2005 (Friday) he knew what to say and hard to organize thoughts how to say – no alcohol – ok within a few minutes, INR now – if ok stay 1.0 mg – if low [up] to 1.5 mg and recheck one week req given.

The report also noted “Rx – reviewed food that may influence Coumadin effectiveness – should review list of food to avoid”.

[94] Although Felix Chan’s reading from January 9, 2006 was 1.1 INR Dr. Tang erroneously recorded the reading on his chart at INR 1.4. This was the reading of the previous INR test on December 9, 2005.

[95] As a result of the October 20, 2005 INR reading of 4.5 Dr. Tang reduced Felix Chan’s dosage from 1.5 mg to 1.0 mg. There followed two monthly tests showing readings in a subtherapeutic level. The December 9, 2005 test showed an INR of 1.4 and the January 9, 2006 test showed an INR of 1.1. Although the December 9, 2005 report noted “too low needs increased dosage” there is no evidence that this information was conveyed to Felix Chan. Indeed the note of January 12, 2006 notes that Felix Chan was taking meds regularly at a dose of 1.0 mg daily. There is no notation on this chart about increasing the dose.

[96] As a result of the January 12, 2006 visit Dr. Tang ordered another INR test. This test was taken at the doctor’s office on Thursday, January 12 and sent to the lab. The result of this test was forwarded to the doctor’s office and a date stamp on the lab report indicates “received January 13, 2006”. The notation on the bottom of the lab report indicates “[increase] dose of Coumadin as I told him at last visit! Recheck one week”. The notation about increasing the dose on the lab form is not reflected in the doctor’s chart from the last visit earlier that week. That chart from Monday simply notes that “has been taking meds regularly 1.0 mg daily”.

[97] Dr. Tang did not see Felix Chan again. On the evening of Friday, January 13, 2006 or early the next morning Mrs. Chan observed her husband in distress in bed. She called 911 and he was transported to hospital where he was subsequently diagnosed with an embolic stroke. Upon admission a further INR test was done and the result was an INR reading of 1.3.

December 23 Transient Ischemic Attack (“TIA”)

[98] On his visit to Dr. Tang on January 12, 2006 Felix Chan spoke about an event that occurred while he was at work on December 23, 2005. For a few moments he had difficulty speaking or collecting his thoughts. These symptoms passed quickly and he did not seek any medical advice that day. Dr. Tang recognized the possibility of a transient ischemic attack (“TIA”). Given that two and half weeks had passed since this event he noted in the chart “if recurs may consider a CT of brain”.

[99] In his evidence for the plaintiffs Dr. Upton explained what a TIA is:

A transient, that is, it doesn’t last very long, ischemic that is a shortage of blood supply, attack. That’s where the T and the I and A come from. Now a transient ischemic attack was traditionally thought to be just a shortage of blood, but we now know that some TIA’s are really little strokes. Now it’s quite common for the patient to have transient ischemic attacks in the same territory of the brain that they are subsequently going to suffer a stroke in.

[100] In his evidence for the plaintiff Dr. Drummond recounted the significance of a possible TIA. As he stated:

O.K. so now we’ve got big trouble, you know, the last 15 years we’d been trying to prevent a stroke given the risk factors of both atrial fibrillation and two mechanical heart valves, that’s why we’ve been involved in this process. Now the patient has come in with the sequela which you don’t want to hear, which is that there may have been an embolic phenomena as related to those three main issues.

[101] Dr. Drummond indicated that, because of this major concern in a high risk individual, management was required in a much more aggressive manner. One option was to consult with a neurologist, another option was to send Mr. Chan to the emergency department. In coming to the opinion that Dr. Tang did not meet the standard of care, Dr. Drummond provided this in support of his opinion with respect to the January 12 visit:

Again in the context of an isolated result of 1.1, it would mandate again an increase in dose – and a discussion of risk….there is now been a subtherapeutic INR for almost a month, it really does require some urgent attention.

[102] With respect to Dr. Tang’s receipt of the test on Friday, January 13, 2006 Dr. Drummond stated:

No I don’t think it’s been reasonable since – since mid-December frankly. This especially in the setting of somebody who’s had a TIA over the Christmas holidays. This is – not even a therapeutic INR; this is practically a normal INR. The patient is unprotected the patient is at risk and the patient has expressed something to suggest that he’s already beginning to experience a process of stroke.

[103] It should be noted that on January 12, 2006 Felix Chan was still on the dose of 1.0 mg Coumadin. This was the dose that Dr. Tang switched Felix Chan to November 7, 2005 after the high INR reading. This was the same dosage that Felix Chan was on until his January 2006 visit. As the plaintiff’s expert neurologist Dr. Upton stated after reviewing the entire history of INR reports for Felix Chan:

But the basic thing is that the whole point about this is that the predictability here is that a dosage of 1.0 mg of Coumadin in this particular patient is almost always subtherapeutic with a rare exception.

[104] Dr. Upton was asked his opinion on what the outcome would have been if Mr. Chan’s dose had been adjusted upward to 1.5 mg sometime between October and December 31, 2005. Dr. Upton opined that “he would not have had the stroke on the balance of probabilities”. Dr. Upton also said that if he was consulted as a neurologist by a family doctor about the INR test of January 10, 2006 with a reading of 1.1 he would “strongly recommend an increase in the Coumadin dose possibly even to 2 for a day or so and then to 1.5”.

[105] Dr. Blankenstein gave evidence for the defence with respect to the standard of care of Felix Chan. He noted that there were some gaps in testing in that Felix Chan did not get INR testing done in June, July, August, September and early October 2005. However when asked about the period from October 20 until the stroke in January 2006 he said “I note that for those days that he had the testing done, he was not in the therapeutic range”. Dr. Blankenstein acknowledged that the stroke was the likely result of Felix Chan not being in the therapeutic range during this period of time. Dr. Blankenstein acknowledged that historically Mr. Chan had never been in the therapeutic range on a dose of 1.0 mg. Dr. Blankenstein pointed to Dr. Tang’s note about “INR weekly” followed by exclamation marks as indicating that Dr. Tang wanted to monitor Mr. Chan closely. But he acknowledged that Dr. Tang had no way to determine if there was weekly testing nor was there any evidence that Mr. Chan had missed any doses of Coumadin. So any inference of noncompliance was not specifically noted in the chart that he reviewed.

[106] Dr. Blankenstein confirmed that a key assumption of his opinion was that on October 11, 2005 Felix Chan was told to have weekly testing. However upon my review of all the evidence I am not satisfied that Mr. Chan was advised to get weekly testing. I base that on the following points:

• None of the three lab requisitions introduced into evidence called for weekly INR testing. The requisition at Exhibit 18 called for monthly INR testing. None of the requisitions were dated and Dr. Tang did not keep a copy of requisitions in his file.
• Felix Chan did get an INR test about one week later. Following the October 11, 2005 visit he had a test on October 20, 2005.
• The November 7, 2005 chart did not specify weekly testing.
• The next INR received by Dr. Tang was December 10, 2005. The results showed an INR of 1.4. Dr. Tang’s note on the test result indicated “too low needs [increase] dosage”. However there was no note to call Felix Chan or to advise him about the dose or to query why weekly testing was not coming in, if such was required.

[107] Another major assumption which Dr. Blankenstein anchored his opinion on was that, following the December 9, 2005 test results, Mr. Chan was told to increase his dose of Coumadin. When asked if a failure to tell Felix Chan to increase dosage would be substandard Dr. Blankenstein ultimately answered that it would be substandard. The series of question and answers leading to his statement is as follows:

Q: He wants to increase the dose?

A: Okay.

Q: He was there; you were not?

A: Correct.

Q: He was the one exercising his clinical judgement?

A: Correct.

Q: He had the benefit of over 15 years of contact with his patient, correct?

A: Okay.

Q: And in his clinical judgement the dose of Coumadin needs to be raised on that date?

A: Okay.

Q: And the records reflect that, correct?

A: Okay.

Q: So he didn’t do it, is that substandard?

A: Okay

[108] With respect to the care offered in January 2006 Dr. Blankenstein was asked:

Q: So why would – it was substandard not to increase the dose on December 10, it not be substandard on January 9 because you have the same information plus another piece which makes it even more dire?

A: Because there’s another pattern where it says it’s even lower so there’s a question of whether or not the patient’s taking medication all together, or missed some doses or why it’s getting lower.

Dr. Blankenstein did not allow that the conduct was substandard but felt it was reasonable to repeat the INR.

[109] Dr. Demetrios Sahlas gave evidence for the defence. Dr. Sahlas is a neurologist who specializes in the area of stroke management. Although he is not a family physician he advises family physicians and is involved in teaching and training them. In reviewing the 15 year period of time that Dr. Tang managed Felix Chan it was his opinion that Dr. Tang exceeded the standard of care. However, he allowed that there were two periods of time where the standard of care was not exceeded. When questioned about the care given for the period following September 25, 1999 he was asked:

Q: Most doctors would either increase it or increase the frequency of testing, but they wouldn’t sit with a mechanical heart valve patient at subtherapeutic for any long period of time. They would want to be reassured by seeing it get into the right range? Right?

A: Yes you’d want to stay with some close monitoring, yes.

Q: Did he exceed the standard of care on this occasion?

A: No he did not exceed the standard of care there.

Later he was asked:

Q: Family physicians have mentees. If a mentee called you up during this period of time, what would you tell the mentee to do?

A: I’d tell him to increase the dose, for sure I think that it was too long of a span.

Q: And so that’s not an example of where of Dr. Tang exceeded the standard of care?

A: That’s not an example no.

Q: And you didn’t draw that to the court’s attention in your report fair enough?

A: My intent was that overall, taking as a whole, his care exceeded the standard of care. If you take a look at specific examples where he may have done something different, well then I have answer you honestly, you know, most physicians would have done something earlier there.

[110] With respect to the period of care from April 30, 2002 to January 9, 2003 the following questions were put to Dr. Sahlas:

Q: So he’s left the patient at an unacceptably high risk of stroke. This is exactly what you tell the family physicians to avoid, so they don’t end up in your clinic right?

A: I agree. I agree.

[111] With respect to the November 7, 2005 office visit Dr. Sahlas notes that the dose was reduced by one-third from 1.5 to 1.0 mg with a note to recheck. He was questioned:

Q: It just says recheck right? You would agree that the standard of care it should have been rechecked at a minimum of one week later having made that significant dose adjustment?

A: That would have been ideal one week later yes.

Q: Okay and that would be the standard of care?

A: Yes.

[112] With respect to the dose change from 1.5 mg to 1.0 mg after the INR reading of 4.5 of October 20, 2005 Dr. Sahlas offered the following explanation:

At a dose of 1.5 mg he now has a level higher than he’s ever had before. So he responds to that 1.5…so he never had such a high level, so it is, it makes a lot of sense that he would think that if 1.5 is now going to give him supratherapeutic levels then perhaps 1.0 is an appropriate dose now. Now admittedly maybe it was a lab error, maybe you didn’t do anything but these are all options that were equally valid that he should have pursued. The problem with Coumadin management is that it’s trial and error overall. Nobody can hit 100 percent throughout the entire period of taking care of a patient. So these dips they occur just because of the nature of all the variables that play and the doctor not having a hardcore algorithm to follow and so forth.

[113] When asked if a dose of 1.25 mg would be more appropriate Dr. Sahlas said:

Well in retrospect that would appear to have been a better decision but I don’t think Dr. Tang had the benefit of looking backwards every time to determine what the better dose would have been.

[114] The December 10, 2005 INR reading was 1.4 and Dr. Sahlas was asked to assume that Mr. Chan was not told and was asked if that would be substandard. Dr. Sahlas did not agree that it was substandard, that it was reasonable to hold off until more measurements were received. When looking at the issue of how Dr. Tang dealt with dose changes he answered “as a matter of fact it makes sense what you’re saying because in retrospect, looking at everything he often called the patient in to make the actual change yes”. Dr. Sahlas went on to note that dealing with Coumadin is a trial and error process. He indicated “I agree with you in retrospect you know that probably with a benefit of looking backwards that would have been the better dose [1.25 mg] for him to be on.”

[115] With respect to the January 9, 2006 INR report Dr. Sahlas acknowledged that he could find no evidence in the chart that there was a phone call to Felix Chan to tell him to increase his dose. With respect to this occasion Dr. Sahlas was pointed to the words in his report that Dr. Tang had exceeded and surpassed the standard of care. About this particular period he stated “that’s my impression of his overall care and he met the standard of care asking the patient to come in before the weekend.”

[116] On each visit Dr. Tang had his charts and records in front of him and he was able to flip back through the chart to note previous INR levels. With respect to looking back at previous lab reports for INR Dr. Sahlas said:

No what I said was if he didn’t look at the immediately recent INR’s that would have been substandard and the reason we’re talking about that was because I was under the impression that perhaps he didn’t document it, because we were discussing it and it’s been brought to my attention thankfully that in fact it is documented. So he did look at the previous INR’s.

[117] With respect to documentation and the incorrect recording of the most recent INR showing 1.4 when it should have been 1.1 Dr. Sahlas said:

Well the documentation wasn’t comprehensive…it is not documented as well as it could have been but I’m not talking about exemplary documentation. I’m talking about what I think his overall quality of care was.

[118] On November 7, 2005 Mr. Chan’s Coumadin dosage was reduced to 1.0 mg. The following question and answer is of assistance:

Q: Just in retrospect doctor you agree and then you’ve got the next test result right? The reason his blood – the reason his INR’s went down was because he cut the dose of Coumadin, correct?

A: That is likely one of the main reasons but I can’t say that it was the only reason.

STANDARD OF CARE

[119] Both counsel provided thorough and comprehensive briefs as to the legal issues before the court including the standard of care, causation and the role of experts. It is clear that courts are required to determine if the standard of care has been breached before analyzing causation in light of such a finding: see Randall (Litigation Guardian of) v. Lakeridge Health Oshawa 2010 ONCA 537; [2010] 27 O.A.C. 371, and Bafaro v. Dowd 2010 ONCA 188, [2010] 260 O.A.C. 70.

[120] As Schroeder J.A. stated for the Ontario Court of Appeal in Crits v. Sylvester, 1956 CanLII 34 (ON CA), [1956] O.R. 132 (C.A.) at page 3:

Every medical practitioner must bring to his task a reasonable degree of skill and knowledge and must exercise reasonable degree of care. He is bound to exercise that degree of care and skill which could reasonably be expected of a normal, prudent practitioner of the same experience and standing, and if he holds himself out as a specialist a higher degree of skill is required of him than one who does not profess to be so qualified by special training and ability.

[121] The trial judge’s approach to the task when faced with a claim based on physician negligence was canvassed by Shaughnessy J. in McLintock v. Alidina 2011 ONSC 137 at para. 44, [2011] O.J. No. 49:

In an action for negligence, the plaintiff has the onus of proving upon a balance of probabilities:

a. That the physician owed the plaintiff a duty of care;

b. The practitioner breached the applicable standard of care;

c. The plaintiff suffered an injury; and,

d. The practitioner’s conduct was the approximate cause of that injury.

[122] In Keith v. Abraham 2011 ONSC 2, [2011] 80 C.C.L.T. (3d) 47, D.M. Brown J. provided a thorough review of the standard of care applicable to health care practitioners. The following points can be drawn from his analysis at para. 213:

• Physicians have a duty to conduct their practice in accordance with the conduct of a prudent and diligent doctor in the same circumstances
• A physician’s treatment is not be judged by its result
• An unfortunate outcome does not constitute proof of negligence
• The conduct of physicians must not be judged in hindsight
• A physician is not to be held liable for mere error of judgment, which is distinguishable from professional fault
• Where a common and accepted course of conduct is adopted based on the specialized and technical expertise of professionals, it is unsatisfactory for a finder of fact to conclude that such a standard was inherently negligent unless any reasonable person would use an obvious existing alternative
• A physician cannot be held accountable for a treatment decision based on unreliable patient data
• The invariable practice of a professional can be given significant weight by a court

[123] In McArdle Estate v. Cox 2003 ABCA 106, 2003 A.J. No. 389 the Alberta Court of Appeal noted that the standard of care is influenced by the foreseeable risk. As the Court stated at para. 27:

The degree of foreseeable risk involved in a procedure or treatment is not only an appropriate, but indeed an essential determinant of the appropriate standard of care. The standard of care is influenced by the foreseeable risk. As the degree of risk increases, so does the standard of care of the doctor... Chief Justice Cardozo (as he then was), a famous American jurist and future U.S. Supreme Court Justice said it in words known to every student of tort law: “The risk reasonably to be perceived defines the duty to be obeyed”. (Palsgraf v. Long Island Railway Co., 162 N.E. 99 at 100 (NY 1928), 248 NY 339;...)

EXPERT EVIDENCE

[124] It is clear that expert evidence is both helpful and necessary to assist the trier of fact in determining whether or not the physician has breached the standard of care. As Carpenter-Gunn J. stated in Bafaro v. Dowd [2008] O.J. No. 3474 (Ont. S.C.) aff’d 2010 ONCA 188, [2010] 260 O.A.C. 70 (C.A.) at para. 31:

Due to the specialized knowledge of the medical profession, expert evidence is needed in medical malpractice cases:

Actions alleging malpractice involve issues to be decided that are not within the ordinary knowledge and experience of the trier of fact. Therefore the Plaintiff requires expert evidence to prove that the Defendant physician was negligent.

…the Court’s findings should be based on expert evidence; and the Court should not make conclusions of breach of the standard of care or causation without expert opinion evidence in support of those conclusions. [Citation omitted]

[125] As is often the case this court is faced with conflicting expert testimony as to the standard of care. In Crawford (Litigation Guardian of) v. Penney 2003 O.J. No. 89 (Ont. S.C.) Power J. stated at para. 248:

I conclude from the foregoing that indeed, the appropriate standard of care is determined by the trier of fact. Where there are conflicting expert opinions, the trier of fact must weigh the conflicting testimony and ultimately assess the weight to be given to the evidence. “There is no necessitated dismissal of a medical negligence claim simply because honest and competent experts disagree over a doctor’s diagnoses and treatment”.

[126] However it is clear that what an expert would have done in a specific situation does not of itself always reflect the standard of care. As Carpenter-Gunn J. stated in Bafaro v. Dowd, at para. 36:

To the extent than an expert testifies as to what he himself would do in a situation, rather than what the standard of care requires, his testimony does not establish the standard of care nor demonstrate that the defendant doctor breached a standard of care.

[127] In Anderson v. Chasney, 1949 CanLII 236 (MB CA), [1949] 4 D.L.R. 71 (Man. C.A.) Coyne J.A. reminded courts at para. 43:

The experts remain witnesses to give their expert opinions and assistance of the jury or the Court to determine whether there is negligence or not. The opinions of experts are not conclusive.

The Role of the Expert Witness

[128] As part of the Civil Justice Reform Project the Honourable Coulter A. Osborne Q.C. chaired a committee which studied a number of potential civil justice reforms including the role of an expert at trial. The Committee’s report, Summary of Findings and Recommendations, (Toronto, Ministry of the Attorney General, 2007), noted:

The issue of “hired guns” and “opinions for sale” was repeatedly identified as a problem during consultations. To help curb expert bias, there does not appear to be any sound policy reasons why the Rules of Civil Procedure should not expressly impose on experts and overriding duty to the court, rather than to the parties who pay or instruct them. The primary criticism of such an approach is that, without a clear enforcement mechanism, it may have no significant impact on experts undully swayed by the parties who retain them.

[129] The report continued:

An expressly prescribed overriding duty to provide the court with a true and complete professional opinion of will, at minimum, cause experts to pause and consider the content of their reports and the extent to which their opinions may have been subjected to subtle or overt pressures. Matched with a certification requirement in the expert’s report, it will reinforce the fact that expert evidence is intended to assist the court with its neutral evaluation of issues. At the end of the day, such a reform cannot hurt the process and will hopefully help limit the extent of expert bias.

[130] The report recommended the following to the Ministry of the Attorney General:

Adopt a new provision (in the Rules of Civil Procedure or Evidence Act) to establish that it is the duty of an expert to assist the court on matters within his or her expertise and that this duty overrides any obligation to the person from whom he or she is received instructions or payment. Require the expert, in an expert report, to certify that he or she is aware of and understands this duty.

[131] As a result of this report the Rules of Civil Procedure, R.R.O 1990, Reg. 194 were amended by the addition of Rule 53.03 which speaks to the role of expert witnesses. Paragraph 53.03(2.1)(7) provides that a report shall contain the following information:

7. An acknowledgement of expert’s duty (Form 53) signed by the expert.

[132] Form 53 requires and expert to acknowledge a number of factors to conclude as follows:

4. I acknowledge that the duty referred to above prevails over any obligation which I may owe to the party by whom or on whose behalf I am engaged.

ANALYSIS OF EXPERT EVIDENCE

[133] Both plaintiffs and defendant called medical experts with respect to the standard of care. There is no doubt that the medical experts had the specialized knowledge required to assist the court in understanding the medical issues. However it falls within the realm of the court to determine how much if any weight should be attributed to the experts.

[134] Dr. Blankenstein, a family physician, gave expert evidence for the defence on the standard of care. His evidence was that Dr. Tang met the standard of care in treating Felix Chan. However I note that he came to that conclusion based on certain assumptions in the evidence. The first assumption was that Mr. Chan was advised to get weekly testing at his visit on October 11, 2005. For reasons already stated I find that that assumption was not borne out by the evidence. Another major assumption made by Dr. Blankenstein was that Felix Chan was told to increase his dose of Coumadin upon Dr. Tang receiving and reviewing the December 9, 2005 test result. As previously noted I am not satisfied that Felix Chan was contacted. Therefore I place less weight on Dr. Blankenstein’s opinion. Dr. Blankenstein also opined in cross-examination that if Felix Chan was not advised to increase his dose on December 10, 2005 that care would be sub-standard. Dr. Blankenstein’s evidence also confirmed that a doctor has certain responsibilities which cannot be delegated to the patient. Although he said that his practice was that patients should call his office to get their test results, if they did not call his evidence was: “I’ll be the one responsible and will be calling them if there’s any area of concern”.

[135] Dr. Sahlas, a neurologist, also gave evidence for the defence on the standard of care. Although he is not a family physician he does teach family physicians about stroke management. Dr. Sahlas’ overall opinion was that Dr. Tang exceeded the standard of care of a family physician. However, he allowed that within the two extensive subtherapeutic periods previously noted Dr. Tang’s care “did not exceed the standard of care”. Although these periods of subtherapeutic INR test results did not contribute to the stroke that Felix Chan had Dr. Sahlas would not allow that the standard of care was not met during this period. Given that Felix Chan had approximately 11 blood tests showing subtherapeutic INR readings from May 9, 2002 to December 11, 2002 without any dose adjustment by Dr. Tang I attribute less weight to his overall opinion that Dr. Tang exceeded the standard of care.

[136] With respect to the events leading up to the stroke including the visits and tests from October 2005 to January 2006 Dr. Sahlas tended to look at each individual action taken by Dr. Tang in isolation. He determined that each was a reasonable step for a family physician to take. I agree with Dr. Sahlas that those events viewed in isolation could be considered reasonable in the circumstances. However I take a different view when I review the constellation of tests and visits that took place from October 2005 to January 2006.

[137] Dr. Sahlas confirmed that a dose of 1.25 mg might have been a more appropriate dose for Dr. Tang to prescribe instead of the 1.0 mg dose prescribed on the November 7, 2005 visit. However Dr. Sahlas said: “well in retrospect that would appear to have been a better decision but I don’t think Dr. Tang had the benefit of looking backwards every time to determine what the better dose would have been”.

[138] In fact Dr. Tang could have had the benefit of looking backwards had he examined his chart more fully. As previously noted he would have observed that a dose of 1.0 mg had not been substantiated as effective for Felix Chan. A dose of 1.0 mg produced eleven subtherapeutic test results from May 9, 2002 to December 11, 2002.

[139] In reaching my conclusion I put more weight on the evidence of the plaintiffs’ expert Dr. Drummond, a family physician who has extensive experience in managing his own patients on Coumadin therapy. In his evidence he noted that Felix Chan was a high risk individual whose care and management required an aggressive approach. Dr. Drummond noted that the possibility of a TIA was particularly troublesome and a family physician always has the option of consulting with a neurologist. As Dr. Drummond noted with respect the January 12, 2006 visit “there has now been a subtherapeutic INR for almost a month, it really does require some urgent attention”. With regard to the low INR readings Dr. Drummond noted:

This is – not even a therapeutic INR; this is practically a normal INR. This patient is unprotected, the patient is at risk and the patient has expressed something to suggest he’s already beginning to experience a process of stroke.

CONCLUSION ON STANDARD OF CARE

[140] In reaching a conclusion that Dr. Tang failed to meet the standard of care for a reasonably competent family physician in his treatment of Felix Chan the following points should be noted:

• Dr. Tang received a lab report showing an INR 4.5 on October 20, 2005 while Felix Chan was on a dose a 1.5 mg. He had three options;

  a. Do nothing and test in one week to determine if this test was an aberration;

  b. Reduce the dose from 1.5 mg to 1.25 mg; or

  c. Reduce the dose to 1.0 mg

  Dr. Tang chose to reduce the dose to 1.0 mg. That was a dosage which had not previously been documented as effective in providing Felix Chan with a therapeutic level of Coumadin.

• Dr. Tang received a test result on December 10,2005 showing an INR of 1.4, a reading which was below the therapeutic range. Dr. Tang correctly noted that the dose should be increased but did not provide what the new dose should be nor did he provide instructions for his staff to call Felix Chan.

• Although Dr. Tang generally contacted Felix Chan to come in when dosages were to be changed no such appointment was arranged by Dr. Tang or his staff upon receipt of the December 10, 2005 INR report.

• On Tuesday, January 10, 2006 Dr. Tang received Felix Chan’s INR test result of Monday, January 9, 2006 showing an INR reading of 1.1. Once again the reading was below therapeutic level as it was on the December 10 test. Dr. Tang requested his staff to call Felix Chan in for an appointment. No telephone advice was given to immediately increase the dose notwithstanding the subtherapeutic test result.

• Felix Chan made an appointment to see Dr. Tang on Thursday, January 12, 2006, that being the first appointment date that was made available to him. Dr. Tang noted on his chart that he “has been taking meds regularly 1.0 mg daily”. Dr. Tang did not tell Felix Chan to increase the dose so that Coumadin would move up into the therapeutic level. Instead he ordered another INR test. That test was taken in his office the same day.

• On Friday, January 13, 2006 Dr. Tang received the results of the previous day’s INR test showing an INR of 1.2. Dr. Tang noted on the test “[increase] dose of Coumadin as I told him at last visit!” However there is no note in Dr. Tang’s chart to confirm that he told Felix Chan to increase the dose or what the dose should be at the last visit.

[141] Dr. Sahlas opined that Dr. Tang’s care should not be viewed as falling below the standard of care because to do so would result in assessing the matter with the benefit of hindsight. In my view Dr. Tang could have had the benefit of hindsight had he thoroughly reviewed his chart especially with respect to his previous prescription of 1.0 mg which proved to be subtherapeutic for an extensive period of time in 2002.

[142] Testing documented that the dosage change prescribed by Dr. Tang on November 7, 2005 was not therapeutic. He then compounded this error by failing to adjust the dose upward when he received the December 10 test and the January 9 test. Felix Chan was a high risk individual who had both atrial fibrillation and mechanical heart valves. His Coumadin level was at a subtherapeutic level for an extensive period of time prior to his stroke. He did not have sufficient Coumadin in his system to provide the anticoagulant therapy that he required.

CAUSATION

[143] I am satisfied that Dr. Tang breached the standard of care for a reasonably competent family physician with respect to the Felix Chan’s management of Coumadin in the weeks preceding his stroke on January 13, 2006. I now turn to the issue of causation. In written submissions the defence framed the causation issue as follows:

373. Causation must be proven on a balance of probabilities. At the opening of trial, the Plaintiffs conceded that the appropriate causation test “basic test” for causation is the “but for” test. The Plaintiffs therefore bear the onus of demonstrating that but for the negligence of the defendant physician, the Plaintiff likely would not have suffered the particular harm in question. In this case, the question is whether, but for Dr. Tang’s alleged breach of the standard, Mr. Chan would have suffered a stroke.

[144] In medical malpractice cases, both acts and omissions may amount to fault and both maybe analysed similarly with respect to causation: see Laferriere v. Lawson 1991 CanLII 87 (SCC), [1991] 1 S.C.R. 541 at para. 161:

[145] The plaintiffs’ burden was reaffirmed in the Supreme Court of Canada decision in Resurfice v. Hanke, 2007 SCC 7, [2007] 1 S.C.R. 333 at paras. 21 and 22:

First the basis test for determining causation remains the “but for” test. This applies to multi-cause injuries. The plaintiff bears the burden of showing that “but for” the negligent act or omission of each defendant, the injury would not have occurred. Having done this contributory negligence may be apportioned as permitted by statute. This fundamental rule has never been displaced and remains the primary test for causation and negligence actions.

Causation Evidence

[146] Having determined that Dr. Tang failed to meet the standard of care for Coumadin management it remains to be determined whether the negligence so found was the cause of Felix Chan’s stroke. Both neurologists gave helpful evidence about the benefits of Coumadin in stroke prevention therapy. Dr. Sahlas for the defence provided:

So Coumadin is commonly used to prevent stroke. It doesn’t prevent 100 percent of strokes but it is particularly effective. It can cut the risk down by 70 percent in people at risk with atrial fibrillation, a particular type of heart rhythm abnormality and also with mechanical heart valves.

[147] Dr. Sahlas went on to note the risks associated with a low INR reading. As he stated:

So with a low INR, the Coumadin isn’t effective because either factors are impeding its effectiveness or the patient’s not taking enough Coumadin so that the INR drops. Once it gets below 1.6 or 1.7 its impact on the coagulation cascade decreases steeply and the patient is not effectively anticoagulated and clots can then form.

As Dr. Sahlas continued:

In general we quote things like if the patient has never had a stroke before the risk of a stroke is something like 4.5 percent per year and with Coumadin it drops 1.5 percent per year.

[148] Dr. Upton a neurologist testifying for the plaintiffs stated:

So the modern times, the last 50, 60, 70 years it’s been realized that the probability of developing a stroke if one has a atrial fibrillation or if one has heart valves that may have been replaced, can be greatly reduced if the blood is thinned, that if it’s allowed to take longer to clot. And that way it’s achieved with medication.

[149] When discussing a patient with symptoms such as Mr. Chan’s, that is mechanical heart valve and arterial fibrillation, Dr. Upton stated:

A patient who has pure simple atrial fibrillation who is less than 75 years old has a risk of blood clots of .5 percent per year.

[150] For patients who have heart valve issues he stated:

If they have valve disease, for example rheumatic heart valve disease then it increases the risk of blood clots to maybe up to 5 percent, 6 percent. If they have the heart valve problems treated with mechanical heart valves, the risk rises even further. Now the figures on this have varied in the various published articles and the reason is that nowadays nobody is allowed to go any length of time with artificial heart valves without being on anticoagulation, I mean, it would unethical. So the whole point is that the combination of atrial fibrillation and heart valve disease is more significant and more severe than either atrial fibrillation alone or heart valve disease alone.

[151] Dr. Upton was asked for his opinion on the likelihood of a stroke assuming that Felix Chan was on a dose of 1.5 mg of Coumadin. He was asked the following question and provided the following answer:

Q: So on a balance of probabilities would Mr. Chan have had the cardioembolic stroke he experienced on January 14 under this scenario?

A: Probably not.

Q: And in this circumstance, can you quantify that reduction if he was increased to Coumadin at a dose of 1.5?

A: Well more probably than not, he wouldn’t have had the stroke is what I simply say.

[152] Dr. Upton was asked to determine the likelihood of a stroke during the entire period from the October 20 test to the end of the year:

Q: On a balance of probabilities would Mr. Chan had the cardiorhythmic stroke that he experienced on January 14, 2006?

A: In my opinion he would not have had the stroke on the balance of probabilities.

[153] When asked if his answer would be different on the assumption that Dr. Tang told Mr. Chan to increase the dose on January 10, 2006:

Q: On a balance of probabilities would Mr. Chan have had the cardioembolic stroke he experienced on January 14, 2006?

A: Probably not but even if he had, it would have probably been less severe.

[154] When asked about increasing the dose closer to the event of the stroke he answered:

A: Well we’re getting very close to the time when he did have a stroke so that it’s becoming progressively more difficult to estimate the probabilities, but the probability is that the stroke would have been less severe.

Q: And once again can you explain that?

A: Yes, there are two reasons. One is that the clot wouldn’t have propagated as much and two, when the clot forms it tends to propagate with other clots around it. Now the Coumadin doesn’t dissolve the old clot, it doesn’t do that, but what it does is it greatly reduces the probability that the clot will gain more bulk by clotting blood around it. So therefore the clot once it had formed and arrived where it did would be much smaller and would cause less trouble.

[155] Dr. Blankenstein, a family physician giving evidence for the defence was also asked about causation. The following questions were posed to him and he gave the following answers:

Q: We know from October 20^th to January 13, 2006 he was not in therapeutic range, using normal approach to calculating that – that variable.

A: Right but I would need to know the timeframe that you are looking for, time and therapeutic range.

Q: Well the time and therapeutic range is zero?

A: No I’m asking the time period, is it three months, six months, a year?

Q: October 20^th to January 13, 2006 time and therapeutic range, zero?

A: Correct.

Q: And that’s why he had a stroke?

A: It was a likely cause, yes.

Conclusion on Causation

[156] Having considered the evidence of the medical experts I am satisfied on the balance of probabilities that Felix Chan’s subtherapeutic dose of Coumadin for several weeks prior to his stroke was the cause of his stroke. Felix Chan was a high risk patient. As well as having atrial fibrillation he had mechanical heart valves. A therapeutic dose of Coumadin prevents clot formation and achieves a 70 percent reduction of the risk of a stroke. He was switched to a very low dose of Coumadin after his INR test from October 20, 2005. Subsequent tests on December 10, 2005 and January 9, 2006 showed INR results substantially below the target range for a person presenting with Felix Chan’s medical history. The tests showed he was at a subtherapeutic level. Simply put he had an inadequate amount of Coumadin in his blood system to prevent the accumulation of clots, clots which can propagate and fly off leading to a stroke.

NEGLIGENCE OR CONTRIBUTORY NEGLIGENCE

[157] The defence submitted that based on the evidence at trial non-compliance by Mr. Chan constituted a defence to the allegation of negligence. Alternatively the defence submitted that Mr. Chan’s conduct contributed to the outcome requiring the court to find that Felix Chan should be found contributorily negligent.

[158] Both counsel made submissions on this issue supported by a book of authorities.

[159] As both parties submitted the duty of a patient was canvassed in Rose v. Dujon, 1990 CanLII 5950 (AB KB), [1990] A.J. No. 844 (Q.B.) at p. 29:

The duty a patient owes to himself is to do everything reasonably necessary to ensure he is not harmed, failing which he exposes himself to the submission that he has be contributorily negligent in the losses suffered by him. That being so, …the patient should be held responsible and accountable for disclosing to his doctor all relevant and pertinent information of which he is aware in order to permit his doctor to make a proper diagnosis.

[160] For an authoritative statement of the applicable standard both counsel referred to the text by E.I. Pickard and G.P. Robertson, Legal Liability of Doctors and Hospitals in Canada, 4^th ed. (Toronto: Carswell, 2007). As the authors stated at p. 368:

Patients have certain duties and responsibilities when seeking medical treatment, including a duty to provide information, to follow instructions, and generally to act in their own best interests. In carrying out these duties they are expected to meet the standard of care of a reasonable patient. If they do not, and the breach of the standard is the factual and proximate cause of their injuries they are contributorily negligent and their compensation will be reduced accordingly. Of course, if the injuries are due exclusively to the patient’s own negligence, the action will be dismissed.

[161] As the defence submitted if the court finds that Felix Chan was contributorily negligent then the provisions of the Negligence Act, R.S.O. 1990 c. N-1 will have application.

[162] On the evidence before me I am satisfied that Felix Chan met the standard of care of a reasonable patient. I am satisfied that the defence of negligence should fail and further that this is not a fit and proper case for a finding of contributory negligence against Felix Chan.

[163] Felix Chan was treated by Dr. Tang for over 15 years. He had numerous medical appointments dealing with Coumadin and other medical issues. He attended for over 200 INR tests. He attended Dr. Tang’s office on several occasions to receive Dr. Tang’s advice about changing dosage upon receipt of certain INR tests. There were substantial periods of time when his tests were satisfactory and no dose adjustments were required. Although he was not always faithful about phoning to get the results it is clear that as the doctor-patient relationship evolved Dr. Tang’s office would call him to arrange an appointment to come in if dosage adjustment was required. In fact he came in to Dr. Tang’s office on November 7, 2005 for a dosage change as a result of a phone call by Dr. Tang’s staff to him when Dr. Tang received the October 20, 2005 INR report. He also came in to Dr. Tang’s office on January 12, 2006 based on the January 9, 2006 INR report. Dr. Tang’s office requested that he come in on Thursday or Friday and he took the first opportunity available to him and came in on Thursday.

[164] Felix Chan had a period of time in 2005 when he had no tests. After the May 10, 2005 test, which was in the therapeutic range, he did not get a further test until October 20, 2005. Because Felix Chan could not testify this period went unexplained. However, Dr. Tang’s office had no system to note if a patient was not getting monthly testing and so he was not called during this period to inquire why no tests were being conducted. Although best practices would indicate that it would be prudent for a doctor to phone a patient if there is a substantial gap in monthly testing I am not satisfied that is the standard of care reasonably expected of a family physician managing Coumadin. However it should be noted that Felix Chan’s test on October 20, 2005 disclosed a 4.5 INR which was in the supratherapeutic level. I am not satisfied that the preceding period of non-testing in any way contributed to his stroke. His stroke was caused by a prolonged period of subtherapeutic Coumadin levels, as documented by a series of INR tests.

[165] Although Felix Chan’s INR’s were very low based on the tests on January 9, 2006 and January 13, 2006 they were not so low as to indicate no Coumadin in his system. I am satisfied that these simply reflected the low dosage he had been on since November 7, 2005. Indeed the INR test at the hospital upon his stroke admission was 1.3, a reading which was consistent with some Coumadin in his system.

[166] For reasons stated earlier I do not accept that Felix Chan ran out of Coumadin and was not taking his dose. The medical experts agree that he was well educated on the effects of Coumadin and there was no record by Dr. Tang over the years of failure to comply with the dose requirements. Dr. Tang’s charting note of January 12, 2006 notes that Mr. Chan “has been taking meds regularly 1.0 mg daily”. I accept Mrs. Chan’s evidence that she and Felix Chan took two sets of pills with them when they travelled overseas. She kept one set in her luggage and he kept the other. They went on a trip to Paris on December 28 for two weeks. It is logical to assume therefore that when Felix Chan returned from that vacation he still had a supply of pills in his possession. Although a strict mathematical count of pills available based on prescriptions written in 2005 may indicate that he ran out of pills, such records do not account for the fact that Felix Chan could have had an accumulation of pills acquired over the lengthy period that he was on Coumadin. Nor was there any evidence that he waited until the last minute to request refills from Dr. Tang or to contact his pharmacy to order a refill.

[167] After the October 20, 2005 test he met with Dr. Tang on November 7, 2005. He then had another test one month later on December 10, 2005 and a further test one month later on January 9, 2006. Although there was no evidence that he called Dr. Tang’s office to receive the result of his December 10, 2005 test, this practice was consistent with the doctor-patient relationship as it evolved. It was often the case that Dr. Tang’s office would call him to arrange an appointment when a test was received that required an adjustment. That is the type of phone message he received as a result of the October 20, 2005 report and the January 9, 2006 report. Dr. Tang’s office also attempted to call him about the result of the test taken on January 12. Unfortunately when the doctor’s office phoned they learned of Felix Chan’s stroke.

COSTS

[168] Counsel may contact the trial coordinator at Barrie to arrange an appointment to speak to the issue of costs, if necessary.

MULLIGAN J.

Released: March 30, 2012