Some Show Benefit but New Study Questions Osteoarthritis Treatment
By Alan R. Gaby, MD
Healthnotes Newswire (February 23, 2006)—The long-awaited results of a large study that evaluated glucosamine hydrochloride and chondroitin sulfate as treatments for osteoarthritis were published in today’s New England Journal of Medicine (2006;354:795–808). While there was some evidence that these treatments are beneficial, the overall results were not statistically significant, and the authors of the study concluded that these supplements “alone or in combination did not reduce pain effectively” in people with osteoarthritis of the knee. Nevertheless, a subgroup of the participants did derive worthwhile and statistically significant benefit, and the new study does not negate a substantial body of earlier research demonstrating positive results. Further, there is reasonable evidence that glucosamine sulfate—a different form of glucosamine than that used in this study—and chondroitin sulfate may still benefit people with osteoarthritis.
More than 1,500 people with painful osteoarthritis of the knee were randomly assigned to receive one of five treatments for 24 weeks: placebo, glucosamine (as glucosamine hydrochloride, 1,500 mg per day), chondroitin sulfate (1,200 mg per day), both glucosamine and chondroitin sulfate, or celecoxib (Celebrex; an anti-inflammatory drug).
The proportion of people who responded positively to treatment (defined as a decrease in pain of at least 20%) was 60.1% in the placebo group, 64% with glucosamine, 65.4% with chondroitin sulfate, 66.6% with the combination of glucosamine and chondroitin sulfate, and 70.1% with celecoxib. Although the response rates were slightly higher in the three supplement groups than in the placebo group, none of the differences were statistically significant.
However, when people who began the study with moderate to severe pain were analyzed separately (excluding those with mild pain), the response rate was significantly better with combination therapy than with placebo (79.2% vs. 54.3%). In that subgroup, the response rate to glucosamine plus chondroitin sulfate was actually higher than that for celecoxib (69.4%).
It is not clear why people with different pain severity had different responses to the supplements. It is possible that the unusually high response rate in the placebo group masked a beneficial effect of glucosamine and chondroitin sulfate in the group with mild pain.
A limitation of the study is that researchers used glucosamine hydrochloride, rather than glucosamine sulfate. In previous studies, glucosamine hydrochloride has shown questionable benefit, while glucosamine sulfate has shown more consistent and pronounced benefits. Preliminary research suggests that the sulfate molecule is necessary for glucosamine to exert its maximal effect.
Furthermore, while the study was long enough to demonstrate improvement in pain, it was too short to properly evaluate whether the treatment could slow disease progression. Previous studies lasting two years or longer have shown that taking glucosamine sulfate or chondroitin sulfate slows the progression of knee osteoarthritis. Consequently, even if these treatments do not relieve pain, they might help prevent osteoarthritis from getting worse.
The authors did not find that these supplements generally improve osteoarthritis of the knee. However, as a subgroup of participants did benefit and previous research has shown benefit, people seeking treatment for osteoarthritis of the knee may still consider their use, especially until further research determines whether or not they keep the disease from progressing.
An expert in nutritional therapies, Chief Medical Editor Alan R. Gaby is a former professor at Bastyr University of Natural Health Sciences, where he served as the Endowed Professor of Nutrition. He is past-president of the American Holistic Medical Association and gave expert testimony to the White House Commission on Complementary and Alternative Medicine on the cost-effectiveness of nutritional supplements. Dr. Gaby has conducted nutritional seminars for physicians and has collected over 30,000 scientific papers related to the field of nutritional and natural medicine. In addition to editing and contributing to The Natural Pharmacy (Three Rivers Press, 1999), and the A–Z Guide to Drug-Herb-Vitamin Interactions (Three Rivers Press, 1999), Dr. Gaby has authored Preventing and Reversing Osteoporosis (Prima Lifestyles, 1995) and B6: The Natural Healer (Keats, 1987) and coauthored The Patient's Book of Natural Healing (Prima, 1999).
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