Physical Performance and Central Nervous System-Active Analgesics Independently Predict 8-Year Fall Risk in Adults with or at Risk for Knee Osteoarthritis.

OBJECTIVE: To determine whether baseline objective physical performance and central nervous system (CNS)-active analgesics use independently and jointly predict long-term fall risk among adults with or at risk for knee osteoarthritis (OA). DESIGN: Prospective longitudinal cohort study. SETTING: Community-based cohort from the Osteoarthritis Initiative. PARTICIPANTS: A total of 4,783 adults aged 45-79 years with or at risk for knee OA. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Baseline exposure included CNS-active analgesic use (opioids or antidepressants). Physical performance was assessed using the repeated chair-stand test and 400-m walk test. The primary outcomes were the incidence of any falls (≥1) and recurrent falls (≥2) over 8 years. Associations were estimated using generalized estimating equations adjusted for demographic characteristics, body mass index, and depressive symptoms. RESULTS: CNS-active analgesics use at baseline was associated with higher odds of any fall (adjusted odds ratio [AOR]: 1.16; 95% confidence interval [CI]: 1.08-1.24) and recurrent falls (AOR: 1.30; 95% CI: 1.18-1.42). Poorer physical performance was also associated with increased fall risk. Slower 400-m walk times and inability to complete the chair-stand test were independently associated with both outcomes. No statistically significant interaction was observed between analgesic use and physical performance measures. CONCLUSIONS: Among adults with or at risk for knee OA, CNS-active analgesic use and impaired physical performance were independent predictors of long-term fall risk. Routine assessments of physical performance help clinicians identify individuals at greater risk of falls when prescribing CNS-active medications and guide the development of tailored fall-prevention strategies in rehabilitation.