---is that they go out of date, as this paper in the Annals of Internal Medicine reminds us.
So what, you’re thinking to yourself. All medical literature goes out of date!
OK, here’s what: Some EBM mavens worship the systematic review. Most EBM resources rate systematic reviews at the top of the evidence hierarchy, thus encouraging clinicians to preferentially seek systematic reviews to answer clinical questions. Many contain links that search only systematic reviews
Search strategies which focus on systematic reviews ignore randomized controlled trials published since the latest review and thus may not yield the best and most current evidence.
A quick Google image search reveals that the vast majority (although not all) evidence pyramids rank the systematic review at the top.