• 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.

    • Excellent post we are all biased in some ways.

    • You make a good case, and you are winning the argument, but let me offer a couple of counters. First, I am sure you remember McAllen, Texas. Let us look at it from the other side. Why dont all docs practice like the ones in McAllen? Imagine that docs were investment bankers. Profit maximization would be the norm.

      I also think that part of the problem we are addressing here is anecdotal experience being placed ahead of the literature. I have seen this many times. The surgeon who has the one bad outcome will prioritize that in his practice over what the literature says he should do.

      To be clear, financial incentives are important. In the absence of data they may be dominant. I agree that the use of financial incentives to help control spending is a good idea, but I think if it is couched as quality care with data to support it, physicians will be more responsive.


    • would you recommend any changes to the medical school curciculum to address this issue? maybe requiring more biostats/epi classes? My impression is that many physicians don’t know how to interpret a lot of these studies not understanding p-values, positive predictive values, etc.

    • And of course, as Kevin Drum points out, if you as a patient can have a chance to prevent or catch a cancer earlier in defiance of all reason evidence and so on, since it’s your life, you’re going to have strong desire to err on the side of caution and cost.

      The only solution to the problem I see is to perfect nanites and then just let them do all the work removing the little bits. I honestly have not been able to think of a problem that cannot be helped by use of nanites.

    • There’s pretty strong evidence that dietary fat has no important role in heart disease, and decent evidence to suggest that the conventional interpretation of blood cholesterol levels is completely wrong. Yet you still get a massive effort to make people eat less fat and to take endless amounts of statins to control their lipid levels.

      I think current medical practice is pretty good at acute care for well-defined conditions, but it’s much less good at dumping questionable medical hypotheses, particularly if there’s a lot of profit coming out of following those hypotheses.

      • I am interested in reading the “pretty strong evidence” that saturated fat plays no role in heart disease. Could you pass along a source that I could investigate this further? Thanks.

        • a nice summary of the lack of evidence is gary taubes’ book “good calories, bad calories”. there was never a good reason to believe that saturated fat is bad for you, and the studies that purport to prove it have deep flaws (like, the actual amount of calories from carbs are more than the calories the rats are getting from fat)
          it is however “very obvious” to all that fat makes you fat, so maybe you don’t need a better reason than that to start investigating??

          • My interest concerns thin people like my husband who end up with almost complete blockage in 6 arteries and only slightly elevated cholesterol numbers.

            • I think the book is still useful for that, as he somewhat covers the problem with judging heart health on measures like cholesterol (hint, it is a little bit like the old saying “if all you have is a hammer the whole world looks like a nail”: cholesterol is easy to measure. that does not make it the best measure of heart health).
              there are lots of books and blogs out there summarizing the problems with relying on cholesterol levels as a measure of heart health. what have you read so far?
              another point: the correlation b/w thinness and health?
              not clear at all.

    • Here’s an op-ed from 2009 where an MD insists that “ideology trumps evidence”:


      –Studies have shown that beta blockers in the early stages of a heart attack do not save lives, but cause heart failure in some patients.
      –No cough syrup is better than placebo
      –Antibiotics are more likely to hurt than help patients with ear infections, bronchitis, sinusitis, and sore throats
      –Back surgeries are no better than non-surgical options, but 600,000 are performed per year
      –$3 billion per year is spent on a type knee surgery that has been shown to be no better than a fake surgery

      But doctors still keep prescribing and performing things that they should know don’t work.

    • And then you have patients like my wife, a mid-40’s woman who had a routine mammogram (‘cuz you have too, donchaknow) last fall. The mammogram turned up a mass smaller than a pea, but when she learned of it, she immediately scheduled a needle biopsy. Well, they had problems that prevented them from completing the needle biopsy, so she had to schedule a surgical biopsy. The surgey went off without a hitch – if you don’t count the tremendous anxiety she felt – and the results were negative. It was a huge relief for her, and that was the primary reason she opted for the biopsies: to get a definitive answer.

      Having seen the emotional and physical turmoil she went through for such a tiny spot on her breast, I have to ask what was gained through all of this?

    • Among other authors, I have read Caldwell Esselstyn, Barry Zaret and lots of info put out by the American Heart Association. Thanks for the book recommendation. I will check it out.