Beware the behavioral bias that ‘intervention is better’

One of my professors in medical school once told me that if a medical study evaluating an intervention shows a positive result, it is readily accepted and often even considered a landmark study (used to influence decision making and guide patient care). If a study is negative, however, it is viewed as interesting and probably worthy of further investigation (though sometimes a negative study is just ignored).

In medicine, and in many aspects of life, there is a bias to “do something.” People like to believe that they can fix problems. Positive studies are empowering. It probably helps that surgeons earn a living by operating, and a little encouragement to operate probably goes a long way.

I’m prompted to remark on this after a study in the New England Journal of Medicine evaluated a common knee surgery to remove torn cartilage (meniscectomy). The trial showed that surgical intervention was no better than sham surgery (an incision without an actual intervention). One year after the intervention, both sets of patients had similar outcomes.

This is not the first time this type of finding has been documented. Another study of arthroscopic knee surgery published in NEJM back in 2008 showed surgery was no better than placebo. Similar findings have been produced for injections of hyaluronic acid into the knee. For this intervention, data have been variable, with some studies showing some benefit.

I think this is noteworthy because patience and good judgment are as important as technical skill. Interventions that show small benefits should be viewed with a skeptical eye, especially because interventions themselves usually come with some risk and/or cost.

Fortunately for me, some lessons have broad applicability. The same traits of prudence, caution and patience are as valuable in investing as they are in recommending surgery.

In this vein, I am reminded of a favorite quote: “Never underestimate the value of doing nothing.” –Winnie the Pooh (A.A. Milne)

sources: Arthroscopic Partial Meniscectomy versus Sham Surgery for a Degenerative Meniscal Tear (New England Journal of Medicine); The New England Journal of Medicine: A Randomized Trial of Arthroscopic Surgery for Osteoarthritis of the Knee; The Journal of American Medical Association: Intra-articular Hyaluronic Acid in Treatment of Knee Osteoarthritis

Author’s note: For more on this topic, I recommend another thoughtful blog: Doctor Skeptic

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1 comment for “Beware the behavioral bias that ‘intervention is better’

  1. January 27, 2014 at 1:51 am

    The human body has an incredible ability to heal itself, but it’s human nature to act and act quickly. Patience is an art to say the least, even when practiced in science 🙂

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