Peter Wehrwein


So you just knew this study would be an attention grabber and kick up a Twitterfest.

Harvard researchers reported results in this month’s JAMA Internal Medicine showing better mortality and hospital readmission statistics for patients treated by female physicians than those treated by their male counterparts.

It seems like we should want a Martha, Mary, or Michelle Welby as our doctor, not a Marcus.

But the result doesn’t go against the grain. Aledade CEO Farzad Mostashari spoke for many when he tweeted, “My priors are confirmed.”

The researchers used a random sample of Medicare fee-for-service beneficiaries who were hospitalized for a medical condition and treated by a general internist (surgeons weren’t included) to conduct their study.

Expressed as a percentage, the female and male physician differences weren’t all that eye-popping. The 30-day mortality for patients treated by female internists was 11.07%. For patients treated by men, it was 11.49%, a 0.43 percentage point difference. When they put the results through a numbers-needed-to-treat analysis, they found that it would take 233 patients to be treated by female physicians to prevent one death.

The results for hospital readmissions were in the same ballpark.

It was when they extrapolated their results that they became impressive—although extrapolations are, by nature, speculative. By their reckoning, 32,000 fewer Medicare beneficiaries would die each year if male internists achieved the same outcomes as female internists.

As Ashish Jha, MD, the senior author, noted on his blog, An Ounce of Evidence, that is roughly the number of Americans who die in car crashes every year (there has been an uptick in motor vehicle deaths and the National Highway Traffic Safety Administration counted 35,092 in 2015).

But, as Jha noted, we really shouldn’t need to be hit over the head with the extrapolation. Imagine, he wrote in his blog post, a new treatment came along that lowered 30-day mortality for hospitalized patients by nearly half a percentage point:

Would that treatment get FDA approval for effectiveness? Yup. Would it quickly become widely adopted in the hospital wards as an important treatment we should be giving our patients? Absolutely. So while the effect size is not huge, it’s certainly not trivial.

(Full disclosure: I wrote a favorable profile of Jha several years ago for the Harvard School of Public Health’s magazine.)

Similarly, if we are really moving toward value-based care and payment, then maybe female physicians will end up getting paid more, not less, than their male peers.

The obvious question is what accounts for the difference in outcomes. This study doesn’t get into reasons why, although they offered some ideas. And a caution: It is an observational study and there’s always the risk of confounding that hasn’t been accounted for. For example, the women internists in this study were younger than the men (42.8 vs. 47.8), although Jha and his colleagues made adjustments for that.

The more favorable outcomes for female internists may have something to do with how women tend to practice medicine. As Jha and company point out, studies of primary care settings have found that women are better about following evidence-based medicine. Women also do better when it comes to some measures of patient-centered care.

Let’s put aside the threadbare, jokey but not funny references to Mars and Venus. The serious takeaway from this study is researchers should take a look at how male internists are practicing medicine. If they are lagging behind on following good evidence, they need to change for the sake of their patients.