StATS: What percentage of medical decisions are based on good evidence? (December 29, 2006)

A correspondent on the evidence based health list noted a commonly quoted statistic that only 10% of all medical practices are based on solid evidence (e.g., randomized trials) and asked for any recent data either supporting or refuting this statistic. I shared several resources that I was aware of:

Robert Todd Carroll offers some historical perspective at

Dr. Carroll, with the help of some colleagues, traces the 10% figure back to a 1968 study by Dr. Kerr White. Apparently, this was an armchair estimate and was not based on any hard data. Anoter consideration, as outlined in an Office of Technology Assessment report is that many medical decisions are based on reasonable, but not rigorous evidence, such as "the use of vitamin B12 to treat pernicious anemia and cast application for forearm fracture." Not cited by Dr. Carroll is the humorous report in BMJ, Parachute use to prevent death and major trauma related to gravitational challenge: systematic review of randomised controlled trials. Smith GCS and Pell JP. BMJ 2003;327:1459-1461 (20 December), doi:10.1136/bmj.327.7429.1459.

As with many interventions intended to prevent ill health, the effectiveness of parachutes has not been subjected to rigorous evaluation by using randomised controlled trials. Advocates of evidence based medicine have criticised the adoption of interventions evaluated by using only observational data. We think that everyone might benefit if the most radical protagonists of evidence based medicine organised and participated in a double blind, randomised, placebo controlled, crossover trial of the parachute.

Further work trying to identify the proportion of medical practices that are based on solid evidence is summarized in

These authors also mention interventions that are self-evident and do not require proof through randomized trials, such as

blood transfusions, starting the stopped hearts of victims with heart attacks, antibiotics for meningitis, or a tourniquet for a gushing wound.

The authors then discuss research in anesthesia, dermatology, pediatric surgery, hematology-oncology, and general practice that quantifies the proportion of medical practices that are evidence based. While there is substantial variation across the disciplines, the studies produce median percentage of 78% for practices that have some evidence base and a median percentage of 38% for practices that are supported by randomized trials.

Another resource that discusses the proportion of medical practices that are evidence based is

and the results presented in this paper are comparable to the previous paper.

This page was written by Steve Simon while working at Children's Mercy Hospital. Although I do not hold the copyright for this material, I am reproducing it here as a service, as it is no longer available on the Children's Mercy Hospital website. Need more information? I have a page with general help resources. You can also browse for pages similar to this one at Category: Teaching resources.