Objective: To estimate the number of expected cases of myopathy based on the prevalence of lipid-lowering drug use, and to compare this number with the observed number of cases of myopathy due to lipid-lowering drug use in the Netherlands.
Methods: Prevalence of lipid-lowering drug use in 1998 was estimated by using data from the PHARMO record linkage system comprising pharmacy records linked to hospital admission data. The expected number of cases of myopathy was calculated by multiplying the total number of person-years of lipid-lowering drug use by the excess incidence rates of myopathy due to those drugs as reported in the literature. The observed number of cases was obtained from PHARMO and the Dutch Pharmacovigilance Foundation Lareb.
Results: Based on the estimated prevalence of lipid-lowering drug use in the Netherlands in 1998 (n = 520 800), we expected 60 cases of idiopathic myopathy due to hydroxymethylglutaryl coenzyme A reductase inhibitors (statins) or fibric acid derivatives (fibrates). This low number was confirmed by data from PHARMO (n = 11; none of these were related to current use of lipid-lowering drugs) and Lareb (n = 43).
Conclusions: The expected number of statin- or fibrate-related idiopathic myopathy is low and observed numbers are even lower in the Netherlands. This should, therefore, not compromise continued use of lipid-lowering drugs.