To examine efficacy and safety of tramadol for knee or hip osteoarthritis (OA).
Pubmed, Embase, Cochrane Library and Web of Science were searched up to May 2020 for randomized controlled trials (RCTs) comparing any of the following interventions: tramadol 100 mg/day, 200 mg/day and 300 mg/day, and placebo for knee or hip OA. Pain and function were measured at or nearest to twelve weeks for efficacy. Gastrointestinal, cardiovascular and central nervous system (CNS) adverse effects (AEs), and withdrawals were measured for safety. Bayesian network meta-analysis was conducted.
Six RCTs (3,611 participants) were included. Tramadol 100 mg/day (standardized mean difference [SMD]=-0.16, 95% confidence interval [CI]: -0.34 to 0.00), 200 mg/day (SMD=-0.21, 95%CI: -0.37 to -0.06) and 300 mg/day (SMD=-0.30, 95%CI: -0.48 to -0.14) were statistically more effective than placebo in pain relief, but only tramadol 300 mg/day was better than placebo in functional improvement (SMD=-0.24, 95%CI: -0.47 to -0.03). Tramadol 100 mg/day (relative risk [RR]=2.29, 95% credible interval [CrI]: 1.22 to 4.25), 200 mg/day (RR=4.35, 95%CrI: 2.31 to 8.01) and 300 mg/day (RR=6.02, 95%CrI: 3.22 to 11.1) involved a higher risk of gastrointestinal AEs. Similarly, tramadol 100-300 mg/day showed a higher risk of CNS AEs and withdrawals. However, the risk of cardiovascular AEs remained unclear.
Only tramadol 300mg/day showed minimal improvement in pain and function but with increasing AEs compared with placebo. Tramadol may not be sufficiently recommended for knee or hip OA by presented evidence, especially in patients with the risk of gastrointestinal and CNS AEs.