Doctors are human

This is a cross-post from Ezra Klein’s blog, where Austin and I are guest-blogging this week.

wrote last week that I disagreed with Ezra that physicians simply “lacked the evidence” to make correct decisions. I wrote yesterday that they too often ignore guidelines and practice how they like. I still maintain that even when confronted with evidence to the contrary, doctors often still follow their biases.

Many of you disagree, especially, at least according to the e-mails I received, the physicians among you.

Here’s the standard disclaimer. I’m a physician. I teach physicians. Some of my best friends are physicians. But that doesn’t mean we’re not wrong from time to time. Let me give you a specific example.

I imagine some of you have knee pain. I imagine some of you have gone to the doctor for knee pain. I imagine that some of you had arthroscopic surgery recommended to you by your physicians for your knee pain. And, I imagine some of you had it.

There was a study published in the NEJM in 2002 that will blow your mind:


Many patients report symptomatic relief after undergoing arthroscopy of the knee for osteoarthritis, but it is unclear how the procedure achieves this result. We conducted a randomized, placebo-controlled trial to evaluate the efficacy of arthroscopy for osteoarthritis of the knee.


A total of 180 patients with osteoarthritis of the knee were randomly assigned to receive arthroscopic débridement, arthroscopic lavage, or placebo surgery. Patients in the placebo group received skin incisions and underwent a simulated débridement without insertion of the arthroscope. Patients and assessors of outcome were blinded to the treatment-group assignment. Outcomes were assessed at multiple points over a 24-month period with the use of five self-reported scores — three on scales for pain and two on scales for function — and one objective test of walking and stair climbing. A total of 165 patients completed the trial.

They took 180 patients undergoing arthroscopic surgery for knee pain and gave half of them fake surgery. Can you imagine? Let’s ignore the ethical implications of this for a moment and marvel in scientific wonder. This is an amazing study, and a once-in-a-lifetime opportunity to see whether the procedure works.

What did they find? Shockingly, arthroscopic surgery didn’t work for knee pain. When compared with fake surgery, patients saw no difference.

As you can imagine, this caused quite a stir. Past trials showed the procedure worked. But those, of course, didn’t include fake surgery, so it could have been a placebo effect. And it was! This study proved it.

Many people tried to pick apart the study. They disagreed with one aspect or another. So what did researchers do? Another study:


The efficacy of arthroscopic surgery for the treatment of osteoarthritis of the knee is unknown.


We conducted a single-center, randomized, controlled trial of arthroscopic surgery in patients with moderate-to-severe osteoarthritis of the knee. Patients were randomly assigned to surgical lavage and arthroscopic débridement together with optimized physical and medical therapy or to treatment with physical and medical therapy alone. The primary outcome was the total Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score (range, 0 to 2400; higher scores indicate more severe symptoms) at 2 years of follow-up. Secondary outcomes included the Short Form-36 (SF-36) Physical Component Summary score (range, 0 to 100; higher scores indicate better quality of life).

What did they find this time? Again, arthroscopic surgery was no better than medical and physical therapy for knee pain.

Back in 2002, 6 percent of the population of the United States 30 years of age or older and 12 percent of those 65 years of age or older had frequent knee pain from osteoarthritis. In 2009, more than a half-million Americans per year underwent arthroscopic surgery to correct osteoarthritis of the knee, at a cost of $3 billion.

But this is America. If you want to have the procedure, so be it. You get to choose. That’s the way we roll.

My question is, did your doctor recommend it? Did your doctor tell you about this study? Do you think that those who recommend and perform this procedure don’t know about this study, and that if only they had this evidence they’d stop?

Or, do you think physicians are influenced by biases and their personal beliefs? Me? I think they’re human.


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