Docs often aren’t that great at numeracy and risk/benefit

Nice short research report over at JAMA Internal Medicine. “Physician Understanding and Ability to Communicate Harms and Benefits of Common Medical Treatments“. Highlights of the methods:

  • It was a voluntary paper survey to resident and attending internal medicine physicians at 2 academic medical centers
  • It contained 18 questions
    • 10 evaluated understanding of rates of benefits and harms of common medical interventions
    • 8 assessed confidence in responses, use of statistical terms, and awareness of high-value care campaigns
  • They surveyed 117 physicians (response rate 89%)

Let’s start with the understanding of benefits and harms of common medical interventions. On average, almost 80% of physicians overestimated benefits and 66% overestimated harms. But it’s not just those numbers. It’s how off they often were. Here’s the figure:


When asked about how often they talk about absolute or relative risk reduction with patients, or how often they discuss a NNT, more than a third responded “never”. Another 47% said “rarely). Pause and think about that. Less than one percent replied always, and less than 16% replied “sometimes”. The vast majority of docs barely ever discuss these things with patients.

I’m screaming in my office because I feel like it’s all I talk about.

Only 45% of them had heard of “Choosing Wisely”. Only half of those who had used it in patient care.

I was exchanging email about this study with FOB Brad Flansbaum, who noted that the difference in the bands between “right” and “wrong” isn’t always huge. After all, if the ARR is really 0.5%, and someone thinks it’s 3%, is that really a big deal?

I’d argue yes. The flaw there is docs don’t think in terms of NNT. If the ARR is 0.5%, the NNT is 200. If the ARR is 3%, the NNT is 33. Those are different. We need to do better when we talk to patients.*


*Ironically, when it comes to NNT, I care more about this difference than if the correct ARR was 25% and they guessed 50%. The NNT for the former is 4, the NNT for the latter is 2. Both are phenomenal.

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