Reaching the wrong conclusion: residual confounding by indication

To the Editor  In a recent edition of Heart , Potier et al reported the results of a large, observational analysis of the REACH registry.1 The authors sought to retrospectively compare clinical outcomes in angiotensin receptor blocker (ARB) and ACE inhibitor (ACEi) treated patients, using propensity score matching to reduce confounding by indication. They conclude that treatment with ARB was more effective than with ACEi, across a wide spectrum of cardiovascular diseases and with regard to a number of different clinical outcomes. However, we …