Supplements No Better Than Placebo in Slowing Cartilage Loss in Knees of Osteoarthritis Patients

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Title: Supplements No Better Than Placebo in Slowing Cartilage Loss in Knees of Osteoarthritis Patients
URL: http://www.pslgroup.com/dg/22DE8E.htm
Doctor's Guide
September 30, 2008

BETHESDA, Md -- September 30, 2008 -- Glucosamine and chondroitin sulfate, together or alone, appeared to fare no better than placebo in slowing loss of cartilage in osteoarthritis of the knee, according to a study in the October issue of Arthritis & Rheumatism.

However, interpreting the study results is complicated because participants taking placebo had a smaller loss of cartilage, or joint space width, than predicted.

"While these results are of interest, we cannot draw definitive conclusions about the utility of glucosamine or chondroitin in reducing joint space width loss, in part because the placebo group fared better than anticipated based on prior research results," said Josephine P. Briggs, MD, National Center for Complementary and Alternative Medicine, National Institutes of Health (NIH), Bethesda, Maryland. "The results of the study provide interesting insights for future research."

To study whether the dietary supplements could diminish the structural damage of osteoarthritis, interested patients who participated in the Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT) were offered the opportunity to continue their original study treatment in the ancillary trial for an additional 18 months, for a total of 2 years.

The randomly assigned study treatments were glucosamine hydrochloride 500 mg TID, sodium chondroitin sulfate 400 mg TID, the combination of glucosamine plus chondroitin sulfate, placebo, or celecoxib 200 mg QD.

The research team, led by Allen D. Sawitzke, MD, and Daniel O. Clegg, MD, University of Utah School of Medicine, Salt Lake City, Utah, enrolled 572 GAIT participants for the ancillary study.

Participants entering the ancillary study had x-ray evidence of grade 2 or grade 3 knee osteoarthritis in one or both knees using the Kellgren-Lawrence scale. At the end of the ancillary study, the team had gathered data on 581 knees.

"At 2 years, no treatment showed what we determined to be a clinically important reduction in joint space width loss," said Dr. Sawitzke. "While we found a trend toward improvement among those with milder, Kellgren-Lawrence grade 2 osteoarthritis of the knee in those taking glucosamine alone, we were not able to draw any definitive conclusions."

The GAIT researchers expected patients in the placebo group to have a joint space width loss of approximately 0.4 mm over 2 years, based on results of previously published large studies. The study team hypothesised that a loss of <=0.2 mm would show a slowed rate of cartilage loss. The final results, adjusted for baseline joint space width, gender, and other factors, showed the following:

· Glucosamine alone group had the least average joint space width loss of 0.013 mm.

· Chondroitin alone group had an average loss of 0.107 mm.

· Glucosamine plus chondroitin group had an average loss of 0.194 mm.

· Celecoxib group had an average loss of 0.111 mm.

· Placebo group had an average loss of 0.166 mm.

In addition to measuring average loss of joint space width, the study also measured the percentage of participants with progression of their osteoarthritis, defined as a joint space width loss of >0.48 mm over the 2 years.

Overall, those with grade 2 knee osteoarthritis were least likely to have progression of osteoarthritis compared to those with more severe disease. Approximately 24% of participants taking the combination of glucosamine plus chondroitin sulfate showed disease progression, which was similar to placebo, but greater than either glucosamine or chondroitin sulfate alone. The researchers theorise that this may reflect interference in absorption of the 2 supplements when taken together.

The researchers note that the study has limitations, such as a greater-than-expected variability in measurement of joint space width loss and a less-than-expected loss of joint space width in the placebo group.

"Despite the ancillary study's limitations, it has provided us with new insights on osteoarthritis progression, the techniques to use to more reliably measure loss of joint space width, the possible effects of these dietary supplements, and the characteristics of osteoarthritis patients that may best respond, all of which will assist investigators in future studies," said Dr. Clegg.

SOURCE: The National Institutes of Health

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