Aims: Opioid analgesics are commonly prescribed for osteoarthritis. Guidelines provide inconsistent recommendations on the use of opioid analgesics in osteoarthritis and previous reviews are limited in scope, warranting a comprehensive assessment of the evidence in this area.
Methods: This was a systematic review and meta-analysis evaluating the efficacy and safety of opioids for osteoarthritis (knee, hand, hip, spine) compared with placebo. Electronic databases including MEDLINE, EMBASE, CINAHL, PsycINFO, CENTRAL were searched from their inception to October 2020 for eligible randomised placebo-controlled trials evaluating any opioid analgesic for osteoarthritis. The primary outcome was pain at the medium term (≥6 weeks but <12 months). Continuous pain and disability outcomes were converted to a 0 to 100 scale. Effects <10 points were considered very small, 10-19 points small, 20-29 points moderate and >30 points large. Dichotomous outcomes were presented as risk ratios (and 95% confidence intervals). Four authors extracted data and assessed risk of bias. Data were pooled using a random effects model. Quality of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE).
Results: Thirty-six trials (dose range: 10-210 oral morphine milligram equivalent units/day) were included. For the medium term, there was low quality evidence from 19 trials (n=8965) of a very small effect of opioids compared to placebo for pain; mean difference (MD) -4.59 (95% CI -7.17, -2.02) and low quality evidence from 16 trials (n=6882) of a very small effect on disability; MD -4.15 (95% CI -6.94, -1.35). Meta-regression didn’t show a significant association of dose with adverse events or pain relief. Opioids increased the risk of adverse events; RR: 1.43 (1.29, 1.59), but evidence was of very low quality. There were no long-term outcomes data.
Conclusions: For people with osteoarthritis, opioids may provide very small effects on pain and disability, and may increase the risk of adverse events.