Numeracy in Medicine: Clinical Wagers to Estimate Probability in Diagnosis

As has become my custom, I offered a wager on rounds the other day. An nonagenarian had gastrointestinal hemorrhage. He presented with syncope and gross (red) blood per rectum. History was significant for Apixaban for atrial fibrillation, and NSAID use. My questions to the team were: what are the possible etiologies of the bleeding; and which among are most likely? After the diagnostic possibilities were enumerated, I offered my wager: a $10 stake that it is peptic ulcer disease (PUD) at 4:1 odds. If the patient has PUD, a taker of my wager owes me $10. If the patient does not have PUD, I owe the taker the $10 stake multiplied by the odds: $40.

There are several pedagogical and practical reasons I engage my team in these games, most of them pedagogical. First, making a wager about clinical outcomes gives you skin in the game. It is remarkable how, when I assign a stake and odds, the interest level goes up and my would-be wager-takers become carefully attuned to the differential diagnosis and other pieces of data that until then had been glossed over or wholly neglected. Recently, when making a wager about results of a pending echocardiogram, the resident did a much deeper chart dive than had previously been done and found a remote echo which bore on the probabilities for the current wager. I had to reassign the odds in light of this new information. Related to this deeper search for available information about the case, there can be a search for information about the diseases under consideration. It would be folly to try to make a bet about the probability of a disease that you understand incompletely, or not at all. Skin in the game will likely lead you to www.uptodate.com where you can ascertain knowledge about the considered diseases to apply it to the wager.

Countless Hours, Part 3: Uncalibrated Interns and Immediate and Accurate Feedback

Immediate, accurate feedback begets calibration

In this third and final installment of Countless Hours:  How to Become a Stellar Student and An Incredible Intern, I will discuss the role of immediate and accurate feedback for the refinement of a skill, prediction, or prognostication to expert levels.

Imagine you are learning to play golf, but you can't see where your balls are going - it would be very difficult, without any feedback to learn to modify your swing to improve your game.  Similarly, if the feedback you received were from an observer with poor vision, and it was not accurate, you would be trying to calibrate your swing to unreliable information and your game would not improve insomuch as the feedback was inaccurate.  Finally, if you did not receive the feedback on your swings until days later, it would be difficult to analyze it and adapt your game to it, compared with iterative feedback incorporated after each swing.

The same principles apply to learning the practice of medicine.  One of the reasons that the case study books mentioned in the previous post are so instructive is that they provide immediate, and accurate feedback - you get to know if your diagnosis was correct immediately after rendering it, and this feedback, from the experts who wrote the book (often with formal or informal peer review and editing), is presumably as accurate as you can hope for.  Thus, case based practice is a very very effective way to become an expert.

Then there is the "hands on" work you do on the wards and in clinic.  Here, feedback is, on average, less immediate, and less accurate, and this is one of the ways your learning in "real life" scenarios is compromised - but there are several things you can do about it to maximize the immediacy and accuracy of feedback in these environments.