Incidence of Hospitalized Rhabdomyolysis with Statin and Fibrate Use in an Insured US Population

BACKGROUND: The incidence of hospitalized rhabdomyolysis is not well characterized among patients taking statin-fibrate combination therapies. OBJECTIVE: To estimate and compare the rates of hospitalized rhabdomyolysis during periods of exposure to different statins and fibrates. METHODS: We retrospectively identified a cohort of patients who initiated a statin or fibrate between January 1, 1998, and December 31, 2007, using a database of a large US health insurer. Patients were followed for the occurrence of hospitalized rhabdomyolysis, determined by clinical review of medical records. Exposure status during the study period was determined by electronic records of statin and fibrate dispensing. Incidence rates (IRs) and incidence rate ratios (IRRs) for various combinations of fibrate and statin exposure were modeled, using Poisson regression. RESULTS: There were 1,116,805 patients who initiated statin and/or fibrate therapy, with 2.4 million person-years of observation. Seventy cases of hospitalized rhabdomyolysis were confirmed. Adjusted analyses showed a persistent increased risk of rhabdomyolysis with combination therapy, while statin and fibrate therapy alone showed similar, nonsignificant increases in risk. The adjusted IRA for a statin and fenofibrate was 3.26 (95% CI 1.21 to 8.80), while the adjusted IRA for a statin and gemfibrozil was 11.93 (95% CI 3.96 to 35.93) versus statin therapy alone. The individual IRs for statin monotherapy ranged from 0.00 to 3.34 per 100,000 person-years. The number needed to harm was lower for combination statin-gemfibrozil therapy (2753) compared with that for statin therapy alone (454,545). CONCLUSIONS: The incidence of hospitalized rhabdomyolysis is rare, but higher in patients with concomitant statin-fibrate treatment than in patients on statin therapy alone. The rate found in this study is consistent with the known profile of the statin-fibrate treatment option for mixed dyslipidemia.