Rosiglitazone and cardiovascular risk.

To the Editor: The meta-analysis by Nissen and Wolski includes two large trials with primary end points that did not include cardiovascular events. In the Diabetes Reduction Assessment with Ramipiril and Rosiglitazone Medication (DREAM) trial, the observation was stopped when diabetes developed in study patients. In the A Diabetes Outcome Prevention Trial (ADOPT), observation was stopped when unsatisfactory glycemic levels occurred. Since rosiglitazone provided better results than comparators in both trials, the mean follow-up in the rosiglitazone group was longer than that in the control group. These differences were not accounted for in the meta-analysis. For example, in the ADOPT trial, the yearly incidences of myocardial infarction in the rosiglitazone group and the control group were 0.46% and 0.39%, respectively, with an estimated increase in risk in the rosiglitazone group of 18%, rather than 33%, as reported in the meta-analysis. Data on mean follow- up in the DREAM trial were not reported. However, the reported number of patients at all points of follow-up was higher in the rosiglitazone group than in the placebo group. Therefore, the effect of rosiglitazone on cardiovascular end points in longer-term trials could have been overestimated.