Limited Meta-analysis Doesn't Represent Reality of Population with Osteoarthritis

WASHINGTON, D.C., In response to a meta-analysis on chondroitin published in the April 17 issue of the Annals of Internal Medicine, the Council for Responsible Nutrition (CRN), the leading trade association for the dietary supplement industry, reminded consumers that chondroitin is a safe, affordable and beneficial option for helping maintain mobility and reduce discomfort associated with osteoarthritis, particularly when combined with glucosamine.

According to Andrew Shao, Ph.D., vice president, scientific and regulatory affairs for CRN, “Meta-analysis can be a valid tool for scientific evaluation, but also has recognized limitations. One can include and exclude studies in various combinations, but the bottom line is consumers use glucosamine and chondroitin supplements because they work.”

The meta-analysis could have potentially included approximately 300 scientific reports on chondroitin; but the researchers chose to look only at 20 randomized clinical trials. Of those 20 trials, they excluded all but three, advising they selected those three they believe were of the highest quality. In effect, they excluded the majority of the data to reach the conclusion that chondroitin worked no better than placebo. With over 21 million osteoarthritis sufferers in the U.S. alone, a conclusion based on only three studies hardly seems representative of the population in question.

CRN pointed out that several meta-analyses have been previously conducted on chondroitin, glucosamine or a combination of the two, with the outcomes being mixed—some analyses have concluded a significant benefit, while others have not. However, when the entire body of research for glucosamine and chondroitin is reviewed, the majority of individual studies show benefit to some degree.

In an editorial accompanying the meta-analysis in the Annals of Internal Medicine, David T. Felson, M.D., M.P.H., Boston University and Boston Medical Center, who agrees with the conclusions reached by the authors with regard to chondroitin, closes with the statement, “If patients say that they benefit from chondroitin, I see no harm in encouraging them to continue taking it as long as they perceive a benefit.” Said Dr. Shao, “As much as we would like for science to always give us clear answers in black and white, the fact is, science is open to interpretation. Although meta-analysis can be a useful tool to examine results from multiple trials, it is still just one tool, and in this case focused on only a narrow view of the entire body of evidence on the effect of chondroitin supplementation. People want to do what works for them, and for many people, that’s taking glucosamine and chondroitin supplements.”

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