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April 2, 2008

Effect of Aspirin Use on Thiazolidinediones and Cardiovascular Events

JAMA. 2008;299(13):1539-1540. doi:10.1001/jama.299.13.1539-a

To the Editor: Dr Lipscombe and colleagues1 conducted a retrospective study to explore the association between cardiovascular events and thiazolidinediones (TZDs) compared with other oral hypoglycemic agents. However, their study did not report on concomitant use of aspirin among patients on TZDs and oral hypoglycemics. There was no adjustment for aspirin use and dose of aspirin. Therefore, an apparent increase in the risk of adverse cardiovascular events from TZDs may have been observed because concomitant exposure to a confounder that is protective for the adverse outcome (aspirin and cardiovascular events) was not accounted for. This is particularly important since the PROactive Study, which indicated that pioglitazone reduced the composite of all-cause mortality, nonfatal myocardial infarction, and stroke in patients with type 2 diabetes mellitus, did report a similar frequency of aspirin use among patients treated with pioglitazone and placebo (75% vs 72%, respectively).2