[Effectiveness of dietary supplements in patients with osteoarthritis: the doubt persists]

Earlier studies with glucosamines in patients with osteoarthritis have shown conflicting results. A placebo-controlled randomised trial was now carried out in 1583 patients with osteoarthritis. The primary endpoint was a 20% reduction in knee pain between baseline and week 24 according to the 'Western Ontario and McMaster Universities arthritis index'(WOMAC)-score. No statistically significant difference was found between the groups using placebo (60% response), glucosamine (64%), chondroitin sulphate (65%) or combination therapy (67%). The results of this trial do not support the hypothesis that glucosamines have a positive effect on symptoms in patients with osteoarthritis of the knee. However, (a) the chance of a statistically significant difference decreases with increasing magnitude of the placebo response, (b) there was a statistically significant reduction in the patients with moderate to severe pain, (c) when the pain was assessed with the more sensitive 'Outcome measures in rheumatology clinical trials'(OMERACT)-'Osteoarthritis Research Society International'(OARSI)-score, there was a better response in the group given combined treatment, (d) the data on radiological progression and the effects on cartilage markers must still come in, and (e) the efficacy may have been higher ifa different dietary supplement had been used. These questions on the design and the robustness of the study indicate that further studies are necessary.