Rosiglitazone and pioglitazone, two FDA approved thiazolidinediones currently in the U.S. market, were introduced approximately 10 years ago. Thiazolidinediones (TZDs) offered physicians another oral medication option for the treatment of type 2 diabetes. However, in May 2007, safety concerns regarding rosiglitazone surfaced after the publication of a meta-analysis suggested it increases the risk of myocardial infarction (MI) and cardiovascular death.1 In September 2007, a meta-analysis addressed the use of pioglitazone and the risk of cardiovascular events in patients with type 2 diabetes mellitus.2 The results showed a significantly lower risk of death, myocardial infarction, or stroke among a diverse population of patients with diabetes who were taking pioglitazone. Evaluation of the two meta-analyses proposes a potential difference in cardiovascular risk between the two TZDs.
A recent retrospective observational cohort study by Graham and colleagues3 was conducted to determine if the risk of serious cardiovascular harm is increased by rosiglitazone as compared to pioglitazone. The study included patients who were 65 years or older, and who were continuously enrolled for at least 6 months in Medicare Part D and at least 12 months in Medicare Part A and B prior to the use of their first TZD. Patients were ineligible if they were living in a long term care facility, in the hospital, or receiving hospice care. New users of rosiglitazone and pioglitazone underwent follow-up from cohort entry until the earliest occurrence of a study end point, a gap in continuous TZD treatment exceeding 7 days, a prescription fill for a different TZD, a non-end-point hospitalization, or end of the study period. A total of 67,593 patients were in the rosiglitazone group compared to 159,978 patients in the pioglitazone group. The primary outcomes of interest were acute myocardial infarction (AMI), stroke, heart failure, and all-cause mortality, and the composite end point of AMI, stroke, heart failure, or death. Baseline characteristics were similar between the two groups; however, the rosiglitazone group had a larger number of participants receiving a prescription co-payment subsidy.
After a median follow-up of 105 days, the adjusted hazard ratio for rosiglitazone versus pioglitazone was 1.06 (95% CI, 0.96-1.18) for AMI; 1.27 (95% CI, 1.12-1.45) for stroke; 1.25 (95% CI, 1.16-1.34) for heart failure; 1.14 (95% CI, 1.05-1.24) for death; and 1.18 (95% CI, 1.12-1.23) for the composite of AMI, stroke, heart failure, or death. The number needed to harm was 60 (95% CI, 48-79) persons treated for 1 year with rosiglitazone to cause 1 excess event as compared to pioglitazone. The risk of stroke, heart failure, death, and the composite of AMI, stroke, heart failure, or death with rosiglitazone compared with pioglitazone was statistically significantly increased. The risk of AMI was not statistically significant between the two drugs in this study of elderly Medicare patients.
The authors concluded that patients 65 years or older who were initiated with rosiglitazone had an increased risk of stroke, heart failure, death, and the composite of AMI, stroke, heart failure, or death compared to pioglitazone. Due to this evidence and the results ...