An analysis of clinical trials on glucosamine and chondroitin sulfate for treating osteoarthritis has shown that these compounds may have some efficacy against the symptoms of this form of arthritis.

The study, by Timothy E. McAlindon, DM, and colleagues at the Boston University School of Medicine, located 37 studies of the compounds in osteoarthritis by a thorough review of the scientific literature published over more than three decades. Of these, 15 trials published between 1980 and 1998 met their criteria: double-blind, randomized placebo-controlled trials that lasted four or more weeks, tested glucosamine or chondroitin for osteoarthritis of the knee or hip and reported data that the researchers could extract on the effect of treatment on osteoarthritis symptoms.

Six of the 15 trials involved glucosamine and nine used chondroitin. The team used only trials of four or more weeks in duration because of evidence that it may take several weeks for the compounds to have a therapeutic benefit. Only one of the 15 trials was completely independent of manufacturer support.

The team's analysis of the trials had two key facets: a quality assessment to evaluate each of the clinical trials and a meta-analysis, which enabled them to integrate the data from different trials. The trials studied had many methodological flaws and biases, including those that tended to inflate the benefits of the compounds. The team was also concerned that trials having small or negative effects might not have been published, but after contacting study authors and other experts, they could locate no unpublished negative results.

Based on data from the trials, the researchers calculated an overall "effect size" for the two compounds: the figure 0.2 is considered a small effect; 0.5, moderate; and 0.8, large. The researchers calculated an effect size for glucosamine of 0.44 and for chondroitin sulfate of 0.78, but reported that these values "were diminished when only high-quality or large trials were considered."

The study was published in the March 15, 2000, issue of the Journal of the American Medical Association (JAMA). Dr. McAlindon recommends that additional, rigorous, independent studies be done of these compounds to determine their true efficacy and usefulness.

Dr. McAlindon said he would not discourage patients from trying these compounds, "but there is a possibility that they might not work," and that substances labeled as these compounds might not even contain them, due to a lack of regulation. Patients with osteoarthritis are urged not to stop proven treatments and disease-management techniques and to let their physicians know if they are considering use of these compounds.

"About 21 million adults in the United States have osteoarthritis," says Stephen I. Katz, MD, PhD, director of the National Institute of Arthritis and Musculoskeletal Skin Diseases (NIAMS). NIAMS funded this study and helped launch a major clinical trial on the compounds in osteoarthritis, along with the National Center for Complementary and Alternative Medicine (NCCAM). Both are part of the National Institutes of Health (NIH).

In March 2000, NIAMS and NCCAM announced they would jointly initiated the largest multicenter study to date of glucosamine and chondroitin sulfate in order to provide definitive answers about their effectiveness for osteoarthritis. The University of Utah School of Medicine is coordinating a nine-center effort in over 1,000 patients.