Statin-induced myopathy in a usual care setting-a prospective observational study of gender differences

The study aims to identify the occurrence and remission of statin-induced myopathy including patient perception and symptom characteristics with a gender perspective.

The study was designed as a prospective, non-interventional investigation in 192 outpatients receiving statin treatment in usual care with 12 months follow-up. Main outcome measure was myopathy related to statin treatment and classified as probable using WHO criteria for adverse drug reaction (ADR) assessment.

Fourteen percent developed myopathy, risk ratio for women 1.52 [95 % CI 1.37; 1.66] as compared to men. The majority graded their pain as "severe." CK values were within normal range. Eighty percent of the women compared to 43 % of the men reported that the muscular symptoms affected their daily life activities to a moderate or severe extent. For those who stopped treatment, mypopathy was the reason for 70 % of the women and 25 % of the men. There was a difference in mean dose between men with and without myopathy, but not in women. Among the patients with myopathy, 76 % reported other ADRs as compared to 21 % of the patients without myopathy (p = 0.002). Twenty-nine percent of the women and 18 % of the men reported other ADRs.

Women reported a higher frequency of myopathy and other ADRs as well as a larger impact on daily life activities. In men, but not in women, the risk of myopathy was dose-dependent. Patients with myopathy were more susceptible to other statin-induced ADRs which raises the question about common underlying mechanisms.