Thiazolidinediones and the risk of incident congestive heart failure among patients with type 2 diabetes mellitus

Background Clinical trials suggest that thiazolidinediones (TZDs) may increase the risk of congestive heart failure (CHF). However, their effect on the risk of incident CHF in unselected populations has not been thoroughly investigated. Methods Using data from the UK's General Practice Research Database, we conducted a case-control study within a population-based cohort of patients with type 2 diabetes. Cases were identified by a clinical diagnosis of incident CHF and were then classified as possible or probable cases using prescription data. A 90-day drug exposure window was used in the primary analysis, which compared patients prescribed TZDs with those with no prescriptions for anti-diabetic medications. Results We identified 3405 incident cases (2632 probable and 773 possible) of CHF and 32,042 corresponding controls. TZDs were prescribed in 6.4% of cases and 6.3% of controls. Prescription of TZDs was associated with an increased rate of possible or probable CHF (adjusted rate ratio (RR) = 1.24, 95% CI = 1.01, 1.54 and adjusted RR = 1.24, 95% CI = 0.98, 1.58, respectively). Similar results were obtained when using a 180-day exposure window (RR = 1.38, 95% CI = 1.11, 1.72 and RR = 1.44, 95% CI = 1.12, 1.84, respectively). Conclusions Given the totality of the evidence from this and previous studies, the probability of an increased risk for CHF with these agents remains high. However, any increase in CHF risk associated with TZDs may be lower than previously reported. Copyright (C) 2011 John Wiley & Sons, Ltd.