Tuesday, March 20, 2012

The probabiltiy dozen of participatory medicine

Yesterday my rant about uncertainty and probability got quite a bit of play in cyberspace, and I am glad.

Uncertainty is ubiquitous. We consider the odds of rain when choosing what to wear. We do (or at least we should do) a quick mental risk-benefit analysis before buying a burger at Quickie-Mart. We choose our driving routes to work based on the probability of encountering heavy traffic. We do this mental calculus subconsciously but reliably, mostly getting it right. What is odd, though, is that there are certain parts of our lives where we expect complete and utter certainty. I will not get into the political aspects of this fallacy, but I do want to continue down this line of reasoning about healthcare.

As I said yesterday, and many many times in the past, the only certain thing about medicine is uncertainty. And here is what I want you to understand deeply: the amount of uncertainty is much greater than you think. So, every time you say to yourself "I think there is a lot of uncertainty in this information," multiply it by 100, and then you may get close to just how uncertain most information is.

And again, I want to emphasize that this uncertainty gets magnified in the office encounter. So, what is the solution, short of having everyone understand the totality of evidence? Yesterday I said that the solution is to teach probability early and often, and this is indeed the best long-range answer. But is there anything we can do in the short-term? The answer, of course, is yes. And here is what it is.

Everyone needs to learn what questions to ask. Instead of nodding your head vigorously to everything your doctor says, put up your hand and ask how certain s/he is that s/he is on the right track. Here is a dozen questions to help you have this conversation:

1. What are the odds that we have the diagnosis wrong?
2. What are the odds that the test you are ordering will give us the right answer, given the odds of my having the condition that you are testing me for?
3. How are we going to interpret results that are equivocal?
4. What follow-up testing will need to happen if the results are equivocal?
5. What are the implications of further testing in terms of diagnostic certainty and invasiveness of follow-up testing?
6. If I need an invasive test, what are the odds that it will yield a useful diagnosis that will alter my care?
7. If I need an invasive test, what are the odds of an adverse event, such as infection, or even death?
8. What are the odds of missing something deadly if we forgo this diagnostic testing?
9. What are the odds that the treatment you are prescribing for this condition will improve the condition?
10. How much improvement can I expect with this treatment if there is to be improvement?
11. What are the odds that I will have an adverse event related to this treatment? What are the odds of a serious adverse event, such as death?
12. How much will all of this cost in the context of the benefit I am likely to derive from it?

And in the end, you need to understand where these odds are coming from -- the clinician's gut or evidence or both? I prefer it when it integrates both, which, I believe, was the original intent of evidence-based medicine.

Perhaps for some of us this is a stretch: we don't like numbers, we are intimidated by the setting, the doc may be unhappy with the interrogation. But it is truly incumbent on all of us to accept the responsibility for sharing in these clinical decisions. I believe that the docs of today are much more in tune with shared decision-making, and understand the value of participatory medicine. And if they are not, educate them. Ultimately, it is your own attitude to risk, and not just the naked data and the clinician's perceptions of your attitude that should drive all of these decisions.  

Knowledge is empowering, and empowerment is good for everyone, patient and clinician alike. As patients, taking control of what happens to us in a medical encounter can only bring higher odds of a desirable outcome. For physicians, a cogent conversation about their recommendations may help safeguard against future litigation, not to mention augment the satisfaction in the relationship.

And thus starting to discuss probabilities explicitly is very likely to get us to a better place in terms of both quality and costs of medical care. And in the process it may very well train us how to make better decisions in the rest of our lives.

I would love to hear about your experiences discussing probability, be it in a medical or non-medical setting. And as always, thanks for reading.

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