Comparison of Cardiovascular Outcomes in Elderly Patients With Diabetes Who Initiated Rosiglitazone vs Pioglitazone Therapy

Background: Recent meta-analyses have raised the possibility that rosiglitazone maleate may increase the risk of ischemic cardiovascular events, whereas pioglitazone hydrochloride could not be linked to such a risk. We compared cardiovascular outcomes and mortality between patients initiating pioglitazone vs rosiglitazone therapy. Methods: We assembled an inception cohort of Medicare beneficiaries older than 65 years with state-sponsored prescription drug benefits who had diabetes mellitus and initiated treatment with rosiglitazone or pioglitazone between January 1, 2000, and December 31, 2005. The study outcomes included all-cause mortality, myocardial infarction, stroke, and hospitalization for congestive heart failure. Results: Of 28 361 patients selected, 50.3% initiated treatment with pioglitazone and 49.7% with rosiglitazone. Most baseline characteristics were similar between the groups. As preferred in drug safety research, we censored patients at crossover or at 60 days after discontinuation of therapy with their study drug; during 29 060 person-years of follow-up, 1869 patients died. After adjustment for a large number of patient characteristics, Cox regression models revealed 15% greater mortality among patients who initiated therapy with rosiglitazone compared with pioglitazone ( 95% confidence interval, 5%-26%). Use of rosiglitazone was also associated with a 13% greater risk of congestive heart failure ( 95% confidence interval, 1%-26%). No differences between the 2 drugs were found in their rates of myocardial infarction or stroke. Conclusions: Our findings from a large population-based cohort of US seniors are compatible with an increased risk of all-cause mortality and congestive heart failure in patients initiating therapy with rosiglitazone compared with similar patients initiating therapy with pioglitazone. Limitations of this study include residual confounding due to its nonrandomized nature.