Risk of Injury Associated with Opioid Use in Older Adults

OBJECTIVES: To estimate the dose-related risk of injuries in older adults associated with the use of low-, medium-, and high-potency opioids. DESIGN: Historical population-based cohort study: 2001 to 2003. SETTING: Quebec, Canada's, universal healthcare system. PARTICIPANTS: Four hundred three thousand three hundred thirty-nine adults aged 65 and older. MEASUREMENTS: Population-based health databases were used to measure preexisting risk factors for injuries in 2001/02 and drug use and injuries during follow-up (2003). Type and dose of opioids were measured as time-dependent variables, as were other drugs that may increase the risk of injury from sedating side-effects or hypotension. The risk of injury per one adult dose increase in opioid dose was estimated using multivariate Cox proportional hazards models. RESULTS: During the follow-up year, 50.7% of the study population were prescribed drugs with sedating side effects, 15.3% were prescribed an opioid, 20.7% were concurrently using more than one sedating medication, and 3.7% were treated for an injury, fractures (55.1%) being the most common. After adjusting for concurrent drug use and baseline risk factors, low- (hazard ratio (HR)=1.36, 95% confidence interval (CI)=1.33-1.39) and intermediate-potency (HR=1.05, 95% CI=1.02-1.07) opioids were associated with the risk of injury. Use of codeine combinations was associated with the highest risk of injury, a 127% greater risk (HR=2.27, 95% CI=2.21-2.34) per one adult dose increase. (The mean World Health Organization standardized dose in the study population was 1.71 ± 0.85 adult doses.) CONCLUSION: Opioids increase the risk of injury in older adults, particularly codeine combinations.