Current use of analgesics and the risk of falls in people with knee osteoarthritis: A population-based cohort study using primary care and hospital records

OBJECTIVE: To examine the association between the current use of analgesics and the risk of falls in people with knee osteoarthritis (KOA). METHODS: A retrospective cohort study using data from the UK Clinical Practice Research Datalink, with linkage to Hospital Episode Statistics data. People diagnosed with KOA in England between 2000 and 2014 were included. The studied analgesic classes were antidepressants, antiepileptic drugs (AEDs), opioids, non-steroidal anti-inflammatory drugs (NSAIDs) and paracetamol. Cox Proportional Hazards model was used to estimate the risk of fall with current use of analgesics within one year of KOA diagnosis, reported as Hazard Ratio (HR) with 95% Confidence Intervals (CI). RESULTS: This study included 57,383 patients (mean age [SD] 67.0 [12.8] years, 59.3% were female); 44,010 (76.7%) were prescribed analgesics at least once within one year of KOA diagnosis. Within the first six months of KOA diagnosis, the reported HR (95%CI) were 1.46 (1.20, 1.78), 1.40 (0.91, 2.16), 2.40 (2.01, 2.85), 1.72 (1.43, 2.07), 1.98 (1.68, 2.33), while between 6 and 12 months after KOA diagnosis, the HR (95%CI) were 2.68 (2.14, 3.36), 2.22 (1.70, 2.91), 1.96 (1.70, 2.26), 1.47 (1.21, 1.78), 1.92 (1.63, 2.26) for antidepressants, AEDs, opioids, NSAIDs and paracetamol, respectively and adjusted for important potential confounders. CONCLUSION: The current use of analgesics was associated with an increased risk of falls within one year of KOA diagnosis. These findings identify people with KOA who use analgesics as a priority for fall prevention programs/interventions, in an effort to optimise safety of analgesics in this population.