Study designs of evaluations included in the review
Randomised double-blind controlled trials (RCTs) were eligible for inclusion.
Specific interventions included in the review
Trials of TZDs were eligible for inclusion. The TZDs used in the included studies were rosiglitazone (4 to 8 mg daily) and pioglitazone (15 to 45 mg daily). The comparators were placebo, glimepiride, matformin with sulfonylurea, glibenclamide and metformin.
Participants included in the review
Trials that included men with prediabetes or type 2 diabetes were eligible for inclusion. All participants in the included studies had prediabetes or type 2 diabetes. The mean age range was 54.7 to 64 years. Eighty-three per cent of the participants were white and 64.8% were male. With the exception of one study where all the participants had stable NYHA class I-II heart failure at baseline, very few participants in the included studies had heart failure at baseline (range: 0 to 2.5%).
Outcomes assessed in the review
Trials reporting risk or frequency data for congestive heart failure (CHF) and cardiovascular death were eligible for inclusion. The definition of CHF varied between the included studies, though most used investigator-reported or adjudicated events requiring admission to hospital. Data on heart failure events not requiring admission to hospital were excluded. The mean length of follow-up in the included studies was 29.7 months (range: 12 to 48).
How were decisions on the relevance of primary studies made?
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.