Pioglitazone poses same risk as rosiglitazone in insurer's study

Patients faced the same risk of death or cardiac events whether they took rosiglitazone or pioglitazone, according to a new retrospective analysis.

The study included more than 36,000 patients and used information from the database of one insurer (WellPoint). All of the patients began taking either rosiglitazone or pioglitazone between 2001 and 2005, and had no reported prior use of insulin. Propensity scoring was used to control for confounding differences between patients taking the different drugs. The primary outcome was time to acute myocardial infarction (AMI), acute heart failure (AHF) or all-cause mortality. The results were published online last week by Circulation: Cardiovascular Quality and Outcomes.

Of the rosiglitazone patients, 4.16% (602 patients) suffered an AMI, AHF or death compared to 4.14% (599 patients) of the pioglitazone patients. There were no significant differences in risk between the groups for any of the endpoints. The study also looked at the subpopulation of patients who were at least 65 years of age, and found that 355 (13.88%) of the rosiglitazone patients had an event compared with 393 (13.94%) of the pioglitazone patients. The study authors concluded that no significant differences were found between the death and cardiac event risk associated with the two drugs in this study population.

Previous research has found inconsistent results on this question, some of which conflicts with these findings, the authors said. They noted that some other studies which found an increased risk with rosiglitazone included only elderly patients. The current study did include elderly patients, but only ones that had full health coverage, and therefore might still be employed, possibly indicating that they are healthier than other elderly study populations.

That difference is one possible explanation for the failure to find an elevated risk with rosiglitazone, the authors concluded. Another explanation is that both rosiglitazone and pioglitazone confer an additional cardiovascular risk, they said. Further research to refine study methodology, identify at-risk populations and validate events and exposure are needed, especially in light of ongoing legislative and FDA review of rosiglitazone, the authors concluded.