Analgesic use and risk of recurrent falls in participants with or at risk of knee osteoarthritis: data from the Osteoarthritis Initiative

Objective Few studies have compared the risk of recurrent falls across different types of analgesic use, and with limited adjustment for potential confounders (e.g., pain/depression severity). We assessed analgesic use and the subsequent risk of recurrent falls, among participants with or at risk of knee osteoarthritis (OA). Methods A longitudinal analysis included 4231 participants aged 45–79 years at baseline with 4-year follow-up from the Osteoarthritis Initiative (OAI) cohort study. We grouped participants into six mutually exclusive subgroups based on annually assessed analgesic use in the following hierarchical order of analgesic/central nervous system (CNS) potency: use of (1) opioids, (2) antidepressants, (3) other prescription pain medications, (4) over-the-counter (OTC) pain medications, (5) nutraceuticals, and (6) no analgesics. We used multivariable modified Poisson regression models with a robust error variance to estimate the effect of analgesic use on the risk of recurrent falls (≥2) in the following year, adjusted for demographics and health status/behavior factors. Results Opioid use increased from 2.7% at baseline to 3.6% at the 36-month visit (>80% using other analgesics/nutraceuticals), while other prescription pain medication use decreased from 16.7% to 11.9% over this time period. Approximately 15% of participants reported recurrent falls. Compared to those not using analgesics, participants who used opioids and/or antidepressants had a 22–25% increased risk of recurrent falls (opioids: RR_adjusted = 1.22, 95% CI = 1.04–1.45; antidepressants: RR_adjusted = 1.25, 95% CI = 1.10–1.41). Conclusion Participants with or at risk of knee OA who used opioids and antidepressants with/without other analgesics/nutraceuticals may have an increased risk of recurrent falls after adjusting for potential confounders. Use of opioids and antidepressants warrants caution.