Clinical features of patients with statin-related myopathy

Background Although statin-related myopathy is a common adverse event, diagnostic criteria and standard treatments have not yet been established. Furthermore, statin-related myopathy is a major concern because of intolerance and discontinuation of statin agents. Objective To elucidate the clinical characteristics of statin-related myopathy, we retrospectively studied 20 patients with hyperlipidemia who had been receiving statin agents. Results Five of 20 patients developed creatine kinase (CK) elevation, and 2 of these 5 patients developed statin-related myopathy. Statistical analysis of the differences between the CK-high and CK-normal groups revealed that a relatively younger age and hepatic dysfunction were risk factors for statin-related myopathy. Among the 20 patients administered statin agents, patients taking atorvastatin (cytochrome P450 inhibitor) had a high tendency for CK elevation (3/7 patients). The 2 patients with statin-related myopathy were discontinued atorvastatin for four weeks. Statin-related myopathy had gradually resolved. Subsequently, we administered pitavstatin (non-cytochrome P450 inhibitor) for 2 cases. This treatment led to the inhibition and resolution of statin-related myopathy. In the 3 patients with CK elevation without myopathy, we did not change the statin agent. However, these patients did not develop statin-related myopathy. Conclusion We present the detailed clinical characteristics of 5 patients with CK elevation and address our experiences with the control of side effect. This case-oriented study should be helpful to the physicians who directly care for statin-related myopathy patients, and may provide a future direction for performing a more efficient control.