Effectiveness of curcuminoids in the treatment of knee osteoarthritis: a systematic review and meta-analysis of randomized clinical trials

Aim: To critically appraise and evaluate the evidence for effectiveness of curcuminoids in the treatment of osteoarthritis (OA) in adults. Methods: We conducted electronic searches in Medline, Embase, AMED, Cinahl and the Cochrane library. We included randomized controlled trials (RCTs) that investigated the effectiveness of orally-administered curcuminoids in OA in adults, and assessed risk of bias using the Cochrane risk of bias criteria. We used a random-effect model for meta-analysis. Results: We included seven studies with a total of 797 participants with primarily knee OA. All studies were conducted in Asia. The overall risk of bias was moderate. Compared with placebo, curcuminoids significantly reduced knee pain (visual analogue scale): (standardized mean difference: -3.45; 95% CI: -5.52 to -1.38; I-2 = 95% P = 0.001), and improved quality of life (Lequesne pain-function index): (mean difference: -2.69; 95% CI: -3.48 to -1.90; I-2 = 0% P < 0.00001). There were significantly fewer effects on pain relief, knee stiffness and physical function with curcuminoids compared with ibuprofen. Significant improvements in Western Ontario and McMaster Universities Arthritis Index total scores, with significant reductions in the use of rescue medication were also observed with curcuminoids. No serious adverse events were reported. Conclusions: Curcuminoids may have some beneficial effects on knee pain and quality of life in patients with knee OA. However, they are less effective at relieving pain compared with ibuprofen. Curcuminoids appear safe on the short-term, and may reduce the need for rescue medication. Published RCTs vary in reporting quality, are characterized by small sample sizes, and have all been conducted in Asia. Further clinical trials are therefore warranted.