Evidence-Biased Medicine: Part 3

It has been several years since our prior installments on this topic, Part 1 and Part 2.  I was reminded of the subject after reading Dr. Dan Fortenbacher’s blog piece about the lack of attention to the proper identification and treatment of convergence insufficiency in the ophthalmic community, and motivated to comment further after reading this book:

Unhealthy Politics Book Cover

Unhealthy Politics begins with a striking study reported in the New England Journal of Medicine in 2002 that has strong parallels to the 2008 CITT Study published in Archives of Ophthalmology.  The study reported that arthroscopic surgery, performed on millions of Americans suffering from osteoarthritis of the knee, worked no better than a sham procedure in which patients were sedated while the surgeon merely pretended to operate.  About half of the patients who received the real surgery got better; but the same percentage of patients undergoing the sham procedure experienced the same level of improvement, suggesting that the benefits of real or sham surgery were largely due to a placebo effect.  Nor is the knee surgery case an aberration.  In their book Comparative Effectiveness Research: Evidence, Medicine, and Policy, Ashton and Wray note:


The goal of every treatment is to make the patient’s outcome better than it would have been without any intervention.  Because of advances in research in the past six or so decades, clinical scientists are able to estimate with considerable precision whether a particular intervention will lead to net benefit over harm in groups of individuals possessing certain characteristics.  That said, much of clinical practice lacks a supporting evidence base, and what research evidence exists is predominately of poor quality.

A consistent theme in Unhealthy Politics is that a large body of research leaves little doubt that new tests and procedures are often widely adopted before they are rigorously evaluated, and practice norms often do not change quickly and consistently in response to credible evidence.  This has been the case with arthroscopic surgery for osteoarthritis. When the randomized controlled trial results appeared in the NEJM in 2002, orthopedic surgeons were reluctant to acknowledge the validity of the study and its conclusions.  Fifteen years later, the condition is still being managed essentially the same way because doctors feel they know what works and what doesn’t.  While lip service is paid to calls for “evidence”, there is considerable bias in what physicians accept as evidence and how this bias influences the nature of practice.  Sound familiar?


2 thoughts on “Evidence-Biased Medicine: Part 3

  1. In my thinking, the risk to benefit ratio is key. What are the chances of a procedure working (placebo included), and what are the risks (in the case of surgery, permanent mechanical problems, death, etc.)

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