EXTENDED REPORT Associations between Statin use and changes in pain, function and structural progression: a longitudinal study of persons with knee osteoarthritis

Objectives Recently published research suggests that statins may have beneficial structural effects in persons with knee osteoarthritis (OA). The potential effects of statins on patient-reported knee pain and function have not been examined. We studied a large prospective community-based cohort of persons with knee OA to determine if statin usage was associated with changes in knee structure, pain and function trajectories. Methods Data were obtained from the Osteoarthritis Initiative using a subset of 2207 persons with radiographically suspected or confirmed knee OA. The changes in Western Ontario and McMaster Universities Arthritis Index (WOMAC) Pain and Physical Function scores, pain intensity and Kellgren-Lawrence radiographic grade over 4 years were examined. Data from persons were coded based on whether they were incident users of statins over the 4-year period. Outcome trajectories and probability of statin use were examined over the 4-year study period using parallel processing growth curve modelling. The analysis adjusted for potential confounders and determined if statin use predicted outcome trajectories. Results Statin users accounted for 6.7% of the sample in year 1 and 16.4% in year 4. Statin use was not associated with improvements in knee pain, function or structural progression trajectories. The only significant finding indicated that increased duration of statin use was associated with worsening in WOMAC Physical Function scores over the study period (beta = 0.161, p = 0.005). Conclusions Statin use was not associated with improvements in knee pain, function or structural progression over the 4-year study period.