The most critical question when reading a meta-analysis report: Is it comparing apples with apples or apples with oranges?

Abstract

Objective: While the number of meta-analyses published has increased recently, most of them have problems in the design, analysis, and/or presentation. An example of meta-analyses with a study selection bias is a meta-analysis of over 160,000 patients in 20 clinical trials, published in Eur Heart J in 2012 by van Vark, which concluded that the significant effect of renin-angiotensin-aldosterone system (RAAS) inhibition on all-cause mortality was limited to the class of angiotensin-converting enzyme inhibitors (ACEIs), whereas no mortality reduction could be demonstrated with angiotensin receptor blockers (ARBs). Here, we aimed to discuss how to select studies for a meta-analysis and to present our results of a re-analysis of the van Vark data.