• Knee Osteoarthritis
• Osteoarthritis
• Treatment

The apparent efficacy of chondroitin sulfate in treating knee osteoarthritis reported by Reginster et al 1 must be considered in the context of the literature on this subject. The results of trials of chondroitin and/or glucosamine for relief of pain caused by osteoarthritis of the knee and hip have been conflicting. Vlad et al 2 noted that the heterogeneity among trials of glucosamine was larger than expected by chance and examined the reasons for the difference. Trials funded by industry had large effect sizes, and independently funded trials had had no clinically relevant benefit compared with placebo. Potential explanations included a positive bias in industry-funded trials.

A meta-analysis of chondroitin and glucosamine studies found that trials that reported large effects on joint pain were often hampered by poor study quality and small sample sizes.3 The authors concluded that large, methodologically sound trials found small or no effects, as did a meta-analysis of trials of chondroitin.4 A trial of crystalline chondroitin sulfate combined with glucosamine sulfate found no superiority in reducing joint pain or functional impairment compared with placebo.5

None of these trials or meta-analyses, which noted consistent discrepancies between the outcomes of independent and industry-funded trials, was cited by Reginster et al. In light of the apparent positive bias in industry-funded trials, I believe that acceptance of the positive results of this industry-funded study should be withheld pending confirmation by independently funded trials.