Friday, June 5, 2015

On Disagreement. Part 4

"Who shall decide, when doctors disagree, and soundest casuists doubt, like you & me?"
-Alexander Pope

Before Angioplasty and After
Duncan was 67 years old when he had his first heart attack. Squeezing chest tightness came on Friday evening while watching ‘Wheel of Fortune’ and didn’t go away when the puzzle was solved. His wife called 9-1-1, and though the discomfort eased off a bit when the paramedics gave him a few puffs of nitroglycerine, they insisted on bringing him to the hospital. His EKG showed signs of a heart attack and an emergency angiogram showed that one of his three main heart arteries was abruptly and completely blocked, depriving valuable heart muscle downstream from much needed blood flow. The discomfort in his chest finally went away when the small balloon his cardiologist had positioned at the blockage was deflated, revealing that the clot that had been blocking the artery had broken up, restoring the flow of blood. A second inflation of a balloon was required to place a metal stent in the artery to help keep it open over time.

Duncan was lucky: the clot that formed in his heart artery and blocked it off had only been present for a few hours, so not much heart muscle damage had occurred. Untreated, a large territory of heart muscle would have been damaged, leaving him with impaired pumping function, a large scar, and a significant risk of life threatening heart rhythm problems. But the prompt opening of the blocked vessel had averted all of that. In a heart attack, time is muscle.

But Duncan wasn’t completely out of the woods.

His angiogram also showed that one of the other two main heart arteries had an 80-90% narrowing in it. Unlike the clot that blocked off his artery in a few minutes when the contestant bought a vowel, this narrowing was the result of cholesterol deposits in the artery wall that had been slowly building up over years. Interestingly enough, it hadn’t caused him any obvious problems, though in retrospect, he had had some of that chest discomfort before when playing with his grand children, which he’d attributed to indigestion.

Cardiologist #1 admitted Duncan to the coronary care unit (CCU) and told him that some time the following week, this other narrowing should also be treated with a balloon and stent, and that made good sense to Duncan, so he approved.

On Monday morning, cardiologist #2 took over the care of the CCU patients for that week, and after reviewing Duncan’s chart, informed him that the plan would be to continue treating him with a variety of new (to him) medications that had all been shown in randomized trials to reduce his risk of subsequent heart attacks and death. Only if he had problems with chest pain that these medications couldn’t prevent, would he undergo angioplasty and stenting of the remaining 80-90% narrowing. Cardiologist #2 explained to Duncan that other randomized trials comparing angioplasty to treatment with medication hadn’t shown an improvement in survival or reductions in heart attacks when stable patients with one narrowed artery were examined. Why undergo the small but real risks of having a second angioplasty procedure if no obvious benefit seemed likely? Besides, if the artery continued to cause problems despite medication in the future, it could always be treated with angioplasty then.

Duncan regrettably agreed with the new plan, and as soon as cardiologist #2 left the room, he called his nurse with a few questions.

“Do these doctors know what the hell they’re doing? ... How come the first doc said that I should have an angioplasty and the second doc said that I should just take pills? ... What are these people’s credentials?"

The nurse explained that cardiologist #1 was the director of the hospital’s angioplasty program and was recognized as a researcher and leader in the field both nationally and internationally. Cardiologist #2 was the Chief of the Cardiology Department, and the Director of the CCU. She was a co-author of the National Guidelines for the treatment of heart attack victims. He explained that both had many years experience looking after patients like Duncan, and that it wasn’t uncommon for experienced and thoughtful cardiologists to disagree about the best treatment for a given patient. He advised Duncan to make his decision about whether to undergo angioplasty or medical treatment on the basis of his personal values, not the current state of the evidence. Does he prefer the idea of taking medicine, which is simple to do? Or does he prefer taking fewer medicines without minding too much about the risk of another invasive cardiac procedure?

But Duncan couldn’t accept that advice. He wanted to do what was best, not what he seemed to prefer for other reasons.

Cardiologists #1 & #2 represent the larger cardiology community on the question raised by Duncan’s situation. On the basis of their interpretation of the available evidence and experience, some recommend opening the remaining narrowings during the initial stay after a heart attack, while others, on the basis of their experience and interpretation of the same evidence, recommend treatment with medicine and opening the narrowing only if further problems arise down the road. What should Duncan do? What should Cardiologists #1 & #2 do? What should the Cardiology community do?

Should Cardiologists #1 & #2 just continue offering their advice to every patient like Duncan that they see? Should Duncan just flip a coin? Should he get a third opinion?

Isn't it obvious? It certainly was obvious to Duncan! They don’t know the answer and further evidence is required to sort the problem out. In this case, Duncan was lucky, because the cardiology community had recognized that there was, regarding the question posed by his circumstances, a condition known as clinical equipoise. This means that the community had come to the conclusion that they ought to suspend their belief because they just don't know. In fact, a randomized clinical trial (RCT) was developed and was enrolling patients just like Duncan to either medical treatment or angioplasty of the remaining narrowing and following subjects closely for the next 4 years to determine which strategy better improved survival, reduced heart attacks, and improved quality of life. The experiment aimed to recruit almost 4,000 patients.

Some philosophers disagree with the approach to disagreement that I have been arguing for so far. They conclude that it’s perfectly rational for Cardiologst #1 & #2 to disagree. But if that’s true, then it’s perfectly acceptable for each to continue treating patients as they rationally believe. If, say, Cardiologist #1 is rational to believe that the best treatment for Duncan is angioplasty, then it’s unethical for her to enroll Duncan in the trial and expose him to a 50% chance of not getting the treatment that she rationally believes is best for him, and vice versa for Cardiologist #2. If every member of the cardiology community maintained their belief in this fashion, none of them would be able to ethically enroll patients in the trial, the trial would never be completed, and the question would never be answered. It is only by recognizing and accepting that they don’t know the answer that it becomes ethical for disagreeing doctors to enroll their patients in the trial and make progress. Not only has much progress already been made this way, but time and time again, what “thoughtful and reasonable doctors” thought was the best treatment has been shown to do more harm than good when properly tested.

Doctors should be accurate with their patients, and that often means being humble about the community's state of knowledge and their own. They should recognize the limits of their personal assessments based on experience. They should tell patients when there is significant reasonable disagreement, and how confident they are of their advice and why. They should fairly often be saying things like “probably”, “possibly” “we really don’t know”, “our best guess at the moment is”, etc., and patients shouldn't get upset with their doctors when they honestly just don't know.

Cardiologists #1&2 should both tell Duncan that they really don't know what should be done about his remaining 80-90% artery narrowing. They should be free to tell Duncan that each has a hunch about what course of action would be best, but that that's all that they have: a hunch. And this is how the rest of us should behave when faced with the reasonable disagreement of our epistemic peers. Admitting that there is a problem with our belief- a problem big enough to justify suspending a previously held belief-  is the first step towards making sure that our beliefs and the strengths with which we hold them accurately map onto reality.

Notice that Cardiologists #1 & #2 should suspend their belief whether or not a randomized trial addressing the question exists, for the existence of the trial in no way affects their inadequate justification. They should suspend belief before the trial exists, while it is being planned, and until the results are published and shown to warrant one approach over the other.

Next time, I'll be looking at a few objections to the approach to peer disagreement that I have been advocating. Have you got any? Do you disagree?

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