Background/Purpose:  Analgesics including opioids, nonsteroidal anti-inflammatory drugs (NSAIDs), antidepressants, and nutraceuticals are commonly used for pain relief in osteoarthritis (OA). Although it has been reported that opioids and some antidepressants may increase the risk of falls, results from studies assessing the association between analgesic use and falls are mixed. Prior studies were limited by focusing on a single fall as the outcome, and lack of adjusting for pain severity, concurrent use of other medications associated with falls (e.g., anticholinergics), and other potential confounders. Our objective was to assess the association between type of analgesic use and subsequent risk of falls among participants with or at risk of knee OA.

Methods:  We performed a longitudinal analysis with 4 years of follow-up (n=4,511) from the Osteoarthritis Initiative (OAI) cohort study. Analgesic use was identified through medication inventory and/or questionnaires. We grouped patients into 6 exclusive subgroups based on annually assessed analgesic use in the following hierarchical order of potency: (1) opioids, (2) antidepressants, (3) prescription NSAIDs, (4) over-the counter (OTC) NSAIDs/aspirin and other pain medications, (5) nutraceuticals, and (6) no analgesic use. We used multivariate logistic regression with generalized estimating equations to estimate the effect of analgesic use on the subsequent risk of any fall and recurrent falls in the following year, adjusted for sociodemographics, health status/behavior (e.g., pain severity, concurrent use of other medications related to falls), and access-to-care factors.

Results:  Overall analgesic use decreased from 64.8% at baseline to 52.8% at the 4-year follow-up visit. In contrast, opioid use increased from 2.9% to 3.5% over this same time period. In each annual follow-up period, approximately 33% of participants self-reported at least one occurrence of a fall and 15% reported recurrent falls (i.e.≥ 2). Compared to those without any analgesic use, participants in the opioid and antidepressant groups had modest increased odds of both any fall (opioids: adjusted OR [aOR]: 1.37, 95% CI 1.08-1.74; antidepressants: aOR=1.27, 95% CI: 1.09-1.48) and recurrent falls (opioids: aOR: 1.34, 95% CI 1.00-1.80; antidepressants: aOR=1.34, 95% CI: 1.10-1.64; Table 1). Participants in the OTC NSAIDs/other pain medications group had a 24% higher odds of recurrent falls.

Conclusion:  Opioids and antidepressants were associated with a modest increased risk of both any fall and recurrent falls after adjustment for pain severity and other potential confounders, among participants with or at risk of knee OA. Clinical management of pain with opioids and antidepressants among those at risk of falling warrants caution. Future research is needed to exmine and better understand the association between risk of falls and the use of OTC NSAIDs/other pain medications.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/analgesic-use-and-subsequent-risk-of-falls-in-participants-with-or-at-risk-of-knee-osteoarthritis/