Clinical osteoarthritis of the hip and knee and fall risk: The role of low physical functioning and pain medication

Objective: Several studies have found an increased fall risk in persons with osteoarthritis (OA). However, most prospective studies did not use a clinical definition of OA. In addition, it is not clear which factors explain this risk. Our objectives were: (1) to confirm the prospective association between clinical OA of the hip and knee and falls; (2) to examine the modifying effect of sex; and (3) to examine whether low physical performance, low physical activity and use of pain medication are mediating these relationships. Methods: Baseline and 1-year follow-up data from the European Project on OSteoArthritis (EPOSA) were used involving pre-harmonized data from five European population-based cohort studies (ages 65 85, n = 2535). Clinical OA was defined according to American College of Rheumatology (ACR) criteria. Falls were assessed using self-report. Results: Over the follow-up period, 27.7% of the participants fell once or more (defined as faller), and 9.8% fell twice or more (recurrent faller). After adjustment for confounding, clinical knee OA was associated with the risk of becoming a recurrent faller (relative risk=1.55; 95% confidence interval: 1.10 2.18), but not with the risk of becoming a faller. No associations between clinical hip OA and (recurrent) falls were observed after adjustment for confounding. Use of opioids and analgesics mediated the associations between clinical OA and (recurrent) falls, while physical performance and physical activity did not. Conclusion: Individuals with clinical knee OA were at increased risk for recurrent falls. This relationship was mediated by pain medication, particularly opioids. The fall risk needs to be considered when discussing the risk benefit ratio of prescribing these medicationsSources of support: The Longitudinal Aging Study Amsterdam (LASA) is financially supported by the Dutch Ministry of Health, Welfare and Sports (grant no 311669, grant recipient D.J.H. Deeg). The Pe~nagrande study was partially supported by the National Fund for Health Research (Fondo de Investigaciones en Salud) of Spain (grant no FIS PI 05/1898; FIS RETICEF RD06/0013/1013 and FIS PS09/02143, grant recipients A. Otero, M.V. Castell). The Hertfordshire Cohort Study is supported by the Medical Research Council of Great Britain, Versus Arthritis, the British Heart Foundation and the International Osteoporosis Foundation (grant no MRC_MC_UP_A620_1014, grant recipients C. Cooper, E. Dennison). The Italian cohort was supported by the National Research Council of Italy (CNR), Research Project “Aging: molecular and technological innovations for improving the health of the elderly population" (Prot. MIUR 2867, grant recipient: S. Maggi). The Swedish Twin Registry is managed by Karolinska Institutet and receives funding through the Swedish Research Council (grant no 2017-00641, grant recipient Karolinska Institutet