Recent evidence suggests there is an increased risk of rhabdomyolysis in patients initiated on cerivastatin compared to patients initiated on other HMG CoA reductase inhibitors (HMGs). OBJECTIVE: The primary objective is to determine if there are differences among specific HMGs regarding the incidence of rhabdomyolysis. The secondary objective is to identify significant risk factors associated with rhabdomyolysis such as age, gender, and concurrent gemfibrozil use. METHODS: Retrospective pharmacy and medical claims from a large managed care organization were analyzed. Patients were included if they received any HMG (cerivastatin, fluvastatin, atorvastatin, lovastatin, pravastatin, or simvastatin) during the period between 7/1/99 to 12/31/99. All patients were followed for 6 months. ICD-9 diagnosis codes for rhabdomyolysis (idiopathic), myalgia and myositis not otherwise specified, or adverse effect to antilipemics were used to define rhabdomyolysis events. RESULTS: There were 133,454 patients identified who received an HMG during the identification period. The average age was 67.8 years (S.D.=11.1) and 51.5% were female. The rates of rhabdomyolysis with and without concurrent gemfibrozil use were 0.861% and 0.632%, respectively (P=0.13). Overall, the incidence across individual drugs was similar for cerivastatin [0.486%(95%CI=0.363%-0.609%)], fluvastatin [0.679%(95%CI=0.589%-0.769%)], atorvastatin [0.889%(95%CI=0.783%-0.995%)], lovastatin [0.741%(95%CI=0.158%-1.332%)], pravastatin [0.530%(95%CI=0.468%-0.592%)], and simvastatin [0.378%(95%CI=0.212%-0.544%)]. With concurrent gemfibrozil use, the incidence was significantly higher for cerivastatin [6.341%(95%CI=3.005%-9.677%)] compared to fluvastatin [0.713%(95%CI=0.000%-1.439%)], atorvastatin [0.494%(95%CI=0.062%- 0.926%)], lovastatin (0.0%), pravastatin [0.452%(95%CI=0.091%-0.813%)], and simvastatin (0.0%). In a logistic regression model, there was no significant relationship between the incidence of rhabdomyolysis and age or gender. CONCLUSION: In this population, it appears that the risk of rhabdomyolysis is substantially higher when cerivastatin is used concurrently with gemfibrozil. The findings of this analysis indicate there is a substantial need for managed care organizations and pharmacy benefits management companies to proactively prevent the concurrent use of cerivastatin and gemfibrozil.