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Dr West

Evidence, Judgment, and the “Art of Medicine”

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I was recently discussing the debatable point about whether the various PD-1 and PD-L1 inhibitors becoming increasingly available in clinical practice show any clinically significant differences among them (I and many others in the field think they don’t), when in doing so I showed a slide comparing the efficacy and leading side effects of three of the most studied in advanced lung cancer thus far. A colleague with a strong academic background, who I respect and who shows thoughtful judgment, chastised me (somewhat in jest) “but those are cross-trial comparisons! Naughty”.  And it’s true that this approach of comparing results of agents tested in different trials, so called “cross-trial comparisons”, are something we’re taught by statisticians and academic purists is not valid. But the problem is that there is often a marked gulf between the ideal world that we live in at conferences as we debate these points as an intellectual exercise and the real world, where we actually need to make clinical decisions based on incomplete information. In the real world, that means using judgment, but ideally trying to couple that with the best evidence available. 

I must admit that I find that the term “the art of medicine” seems to be invoked all too often as a license to avoid any pretense of weighing evidence and just going with the biases of the physician.  Instead, practicing in the real world should involve using solid evidence when it’s available, allowing room for judgment (such as if a patient is against the evidence-based treatment), but it’s extremely common to need to assess the quality of the best evidence and do the best you can. What are we to do with a patient who has a remote history of an autoimmune disorder or has mild to moderate rheumatoid arthritis? Do we disqualify them from immunotherapy, as just about every immunotherapy trial has? With the promise of immunotherapy, you can make a fair argument that the risk might be worth it.  And pretty much every patient who comes in with compromised liver function or a history of hepatitis C or even, for that matter, a second inconvenient cancer of another type would preclude that patient from participating on the clinical trials that shape our current standards.  We’re left to judge whether we can expect similar results or whether the risks of complicating issues require a deviation. 

We can sniff that we always want to follow the evidence, but only a minority of real world patients are eligible for trials, and few people would accept excluding the teeming masses from treatment just because they are not idealized patients and have inconvenient additional issues.

The key, in my mind, is to prioritize the best quality evidence you have, factoring that in with an informed decision between patient and physician. If there are randomized clinical trials that prove a benefit for a treatment, don’t dismiss that in favor of a hunch or an anecdotal case of someone who happened to do well with an unproven therapy that was highlighted in a TV news snippet (unless it’s in the context of a study that will actually test the value of that therapy).  Despite our intuitive affinity for patient stories, anecdotal cases are the lowest form of evidence and should be viewed like the person in a photo holding a novelty check from the lottery – it’s great, but don’t mistake it for a realistic expectation. But at the same time, physicians can’t be dogmatic and haughty about requiring definitive results from large clinical trials when there’s evidence from databases (retrospective evidence) that one approach is likely better than another (though insurers may be more dogmatic and may refuse to pay for treatments without sufficient evidence). It’s quite common in medicine, especially in cancer care, to need to make a choice without a clear best answer.  Remember, in the land of the blind, the one-eyed man is king.  Imperfect evidence combined with good judgment is better than just categorically refusing to make a decision because you don’t have all of the information you’d like. In the cancer clinic, we often don’t have that luxury.


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