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The October 2008 issue of the journal Arthritis & Rheumatism published the results of the second portion of the Glucosamine Arthritis and Intervention Trial, known as GAIT II. This two-year supplemental investigation examined a small cohort of the original 1,583 participants from the 2006 GAIT study, which was the first large-scale U.S. clinical trial testing whether glucosamine and chondroitin sulfate, used separately or in combination, reduced participants’ pain from knee osteoarthritis.
The follow-up study attempted to assess the effect of glucosamine and chondroitin sulfate on the narrowing of joint space, which often results in knee osteoarthritis pain.
The GAIT II researchers concluded that participants taking glucosamine and chondroitin sulfate, together or alone, did not experience a lessening of cartilage loss in knee osteoarthritis compared to those participants taking a placebo.
In response to GAIT II, the Council for Responsible Nutrition (CRN), the leading trade association representing the dietary supplement industry, issued the following statement from Andrew Shao (Ph.D.), CRN vice-president, scientific and regulatory affairs, about the study’s limitations:
“The results of the GAIT II trial are perplexing and extremely inconsistent with an existing large body of evidence that shows a benefit from glucosamine and chondroitin supplementation. The results are also inconsistent with the first arm of GAIT, as well as with a series of previously published clinical trials that examined the same outcome — the narrowing of the space between joints — and demonstrated a clear benefit.
This trial was a follow-up to the original GAIT trial, using only a small subset of the original cohort of patients. In addition, anecdotal reports from consumers overwhelmingly indicate that glucosamine, chondroitin or their combination are effective.
Although the study found that overall there was no statistically significant difference in the change in joint space width (JSW) among any of the treatment groups — placebo, glucosamine alone, chondroitin alone, the combination of glucosamine and chondroitin, or celecoxib — a series of major limitations with this study render its results questionable.
For example, the original hypothesis that glucosamine and chondroitin or a combination of the two may slow or prevent normal JSW narrowing due to osteoarthritis (OA) can’t be answered by this trial. The researchers expected to see a typical JSW narrowing of approximately -0.4 millimetres (mm). Yet, the actual JSW change in the placebo group was only -0.166 mm, substantially less than what was expected.
Because the placebo group did not worsen as expected, there is no basis for comparison. In addition, the study intended to enroll nearly 800 knee OA patients, but ended up grossly underpowered, with only 357 patients completing the study, due to loss of follow-up and exclusions, making it highly difficult to draw any meaningful conclusions from the results.
Moreover, the results of GAIT II, which examined a subgroup of the same subjects that participated in GAIT I, are directly in conflict with the results of the initial trial. Examining a subset of the same subjects who experienced the most benefit from moderate to severe arthritis pain, GAIT II suggests that the same subgroup who experienced the most pain relief — those using the glucosamine and chondroitin combination — also experienced the most reduction in JSW. These two conclusions are inconsistent, without explanation, to say the least.
The bottom line is that there is a large body of evidence supporting the use of glucosamine and chondroitin as safe and effective in helping individuals who suffer from pain, discomfort and immobility due to OA. The millions of consumers who use glucosamine and chondroitin each year and experience real benefits should continue to feel confident in these products."
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