There’s more to the problem than a lack of evidence

post by Robin Hanson on cancer screenings is getting some play. Robin notes that screening detects more cancer, but doesn’t necessarily save more lives. Ezra Klein thinks that Robin goes a bit too far in his conclusions. To be perfectly clear, I think Ezra has a point; some screening does save lives, and in some cases, it’s just not clear. But I think Ezra himself goes a bit too far here (emphasis mine):

That’s why, if you want to control health-care costs, you somehow need to convince, incentivize or otherwise conscript doctors into doing it for you. Robin Hanson can write as many blog posts as he wants, but as long as doctors are telling scared and uncertain patients that they need to get screened, they’re getting screened. The moment they stop telling patients to get screened, screenings will plummet. In health care, doctors are really the relevant decision-makers. And right now, they don’t have the evidence to make good decisions nor the incentives to make cost-effective decisions.

Look, I’m a physician. At the risk of sounding like a cliche, some of my best friends are physicians. Yet somehow, I keep finding myself in the position of disagreeing with people who are putting physicians on a pedestal.

Too many of you think that we “lack the evidence”, whether it be here, or in terms of cost-effectiveness, or wherever. You think that if physicians were just given the data, we’d all of a sudden practice medicine much better.

Look at Robin’s post. Look at the data on breast cancer screening. Then try and remember when the USPSTF interpreted the data for everyone:

In its first reevaluation of breast cancer screening since 2002, the independent government-appointed panel recommended the changes, citing evidence that the potential harm to women having annual exams beginning at age 40 outweighs the benefit.

At the time, I said this:

Mammograms weren’t outlawed.  They weren’t taken away.  No one’s insurance stopped covering them.  This was a reasoned statement that because the evidence suggests that universal screening of women in their 40s may not be doing more benefit than harm, each woman should make an individual decision with their physician.  It was based on a transparent analysis that anyone could repeat.  Read the full report.

How did physicians respond?

But the American Cancer Society, the American College of Radiology and other experts condemned the change, saying the benefits of routine mammography have been clearly demonstrated and play a key role in reducing the number of mastectomies and the death toll from one of the most common cancers.

And here’s my favorite response (emphasis mine):

“Tens of thousands of lives are being saved by mammography screening, and these idiots want to do away with it,” said Daniel B. Kopans, a radiology professor at Harvard Medical School. “It’s crazy — unethical, really.”

And it’s not just breast cancer. Readers of the blog may remember Austin discussing the evidence about prostate cancer screening.  Fewer of you will remember the mostly ignored cancellation of the USPSTF meeting to update the recommendations on that subject. Evidently, they learned their lesson form breast cancer. We’re still waiting on that update.

So you’ll forgive me for remaining skeptical that physicians just “don’t have the evidence to make good decisions”.  It’s a lot more complicated than that. Physicians are human beings, and just as susceptible to biases as you are. It’s no easier to change their minds, or their behavior, than anyone else’s.

UPDATE: Edited for clarity.

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