How Good are Systematic Reviews?

Interesting article and editorial on currency and value of systematic reviews in current Annals of Internal Medicine. Very relevant for anyone considering the "gold standard" of evidence for clinical practice. Here's the link :

How Quickly Do Systematic Reviews Go Out of Date? A Survival Analysis

Kaveh G. Shojania, Margaret Sampson, Mohammed T. Ansari, Jun Ji, Steve Doucette, and David Moher

Clinicians often use systematic reviews to obtain current evidence to guide clinical decisions and health care policy. Shojania and coworkers studied 100 quantitative systematic reviews to see how quickly the conclusions changed as new evidence became available. Conclusions about the effectiveness or harms of therapies frequently changed soon after publication of the systematic review. The median survival time without a change in the conclusions was 5.5 years. Significant new evidence had become available within 2 years for 23%. The evidence supporting preferred clinical practices is unstable.

Abstract | Full Text | PDF