In 2007 a meta-anlaysis of 42 randomised trials involving rosiglitazone found a 1.4 fold increase in the risk of acute myocardial infarction (AMI) compared with non-thiazolidinedione therapies. Subsequently, a metaanalysis of 19 pioglitazone trials found a significant reduction in a composite outcome of non-fatal AMI, stroke and all-cause mortality. Therefore, this study set out to determine if the risk of serious cardiovascular harm is increased by rosiglitazone compared with pioglitazone.

The study was an observational, retrospective review of the clinical outcomes of 227 571 patients aged 65 years or older who initiated treatment with either rosiglitazone or pioglitazone from July 2006 and who underwent follow-up for 3 years afterwards. The main outcome measures were the individual end points of acute myocardial infarction, stroke, heart failure and all-cause mortality, and a composite end point of all four.

Overall 8867 end points were observed during the study period. Adjusted hazard ratios for rosiglitazone compared with pioglitazone were 1.06 for AMI; 1.27 for stroke; 1.25 for heart failure; 1.14 for death; and 1.18 for the composite endpoint. The attributable risk for this composite endpoint was 1.68 excess events per 100 person-years of treatment with rosiglitazone compared with pioglitazone; this corresponded to a number needed to harm of 60 patients treated for one year.

Conclusions
In this large, retrospective, observational study, prescription of pioglitazone was associated with an increased risk of stroke, heart failure and all-cause mortality in patient aged 65 years and older.

• Graham DJ, Ouellet-Hellstrom R, MaCurdy TE, et al. Risk of acute myocardial infarction, stroke, heart failure, and death in elderly medicare patients treated with rosiglitazone or pioglitazone. JAMA 2010;304:411e18.