Objective: The mechanism of statin-related myopathy is unknown, while its prevalence is probably underestimated. An association between statin-related myopathy and vitamin D deficiency has been reported. In this pilot study we assessed the prevalence of myopathy in statin users attending the outpatient clinic of the Department of Cardiology of a University Hospital from October 2009 to March 2010. We also searched for predictors of myopathy and investigated whether the myopathy was associated with vitamin D deficiency.
Research design and methods: Statin-treated patients were asked to complete an assisted structured questionnaire. Serum creatine kinase (CK) and 25-hydroxyvitamin D (25(OH)D) were measured. Patients with rheumatic diseases, muscle diseases, (poly)neuropathy and peripheral arterial disease were excluded from predictor analysis.
Main outcome measures: Percentage of patients with myopathy in the daily clinical practice of an outpatient clinic, serum 25(OH)D, CK, and predictors of myopathy.
Results: One hundred and four statin-treated patients completed the questionnaire. Serum 25(OH)D was measured in 93 patients. Twenty patients with confounding comorbidities were excluded from analysis. Of the remaining 84 patients, 33% reported myopathy, 24% had myalgia and 6% myositis. Rhabdomyolysis was not observed. Time spent outdoors during winter (≤6 h/week; OR: 10.61; 95% CI: 1.91-58.88), total number of prescribed drugs (1.39; 1.05-1.83), BMI (1.35; 1.07-1.69), CK (1.02; 1.00-1.03) and consumption of fish (≥1/week; 0.19; 0.04-0.89) were predictors of myopathy in multivariate analysis.
Conclusions: Considering the small patient group and a relatively narrow range of vitamin D levels, we arrive at the following statements: 1) one out of three patients reported myopathy; 2) BMI, CK, number of prescription drugs, time spent outdoors and fish consumption were myopathy predictors; and 3) myopathy and 25(OH)D were unrelated.