Comparative Effectiveness of Angiotensin‐Converting Enzyme Inhibitors and Angiotensin Receptor Blockers for Hypertension on Clinical End Points: A Cohort Study

Abstract

Roy and colleagues compared the frequency of new-onset diabetes in hypertensive patients in the community treated with an angiotensin receptor blocker or an angiotensin-converting enzyme inhibitor, concluding that incident diabetes was less frequent in the latter group. However, prospective randomized controlled trials are always preferable to cohort studies for determining the effect of drug therapy on clinical outcomes. Consequently, we were surprised that these authors did not cite either of the two large trials that provide robust estimates of the effect of the drugs in question on the development of diabetes mellitus. The Nateglinide And Valsartan in Impaired Glucose Tolerance Outcomes Research trial (NAVIGATOR)1 showed that valsartan reduced the risk of new-onset diabetes by 14% (95% confidence interval, 8–20%; P<.001), whereas in the Diabetes Reduction Assessment With Ramipril and Rosiglitazone Medication (DREAM)2 trial, ramipril did not have a significant effect on incident diabetes. These findings suggest that the observations of Roy and colleagues are likely to be spurious and probably reflect unmeasured confounding. The ready availability of health system electronic records aggregated into data warehouses provides a wealth of new information, but large numbers of data cannot substitute for methods that are appropriate for the question.