The University of Utah, School of Medicine coordinated this study, which was conducted at 16 rheumatology research centers across the United States. The National Center for Complementary and Alternative Medicine (NCCAM) and the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), two components of the National Institutes of Health (NIH), funded GAIT.
What was the purpose of the study?
Previous studies in the medical literature had conflicting results on the effectiveness of glucosamine and chondroitin sulfate as treatments for osteoarthritis. GAIT was designed to test the short-term (6 months) effectiveness of glucosamine and chondroitin sulfate in reducing pain in a large number of participants with knee osteoarthritis.
What were the key results of the study?
Researchers found that:
- Participants taking the positive control, celecoxib, experienced statistically significant pain relief versus placebo--about 70 percent of those taking celecoxib had a 20 percent or greater reduction in pain versus about 60 percent for placebo.
- Overall, there were no significant differences between the other treatments tested and placebo.
- For a subset of participants with moderate-to-severe pain, glucosamine combined with chondroitin sulfate provided statistically significant pain relief compared to placebo--about 79 percent had a 20 percent or greater reduction in pain versus about 54 percent for placebo. According to the researchers, because of the small size of this subgroup these findings should be considered preliminary and need to be confirmed in further studies.
- For participants in the mild pain subset, glucosamine and chondroitin sulfate together or alone did not provide statistically significant pain relief.
What was the basic design of the study?
In GAIT, participants were randomly assigned to one of five treatment groups: (1) glucosamine alone, (2) chondroitin sulfate alone, (3) glucosamine and chondroitin sulfate in combination, (4) celecoxib, or (5) a placebo (an inactive substance that looks like the study substance). Glucosamine and chondroitin sulfate and their combination were compared to a placebo to evaluate whether these substances significantly improve joint pain. Celecoxib, which is a prescription drug effective in managing osteoarthritis pain, was also compared to placebo to validate the study design.
To reduce the chance of biased results, the study was double-blinded--neither the researchers nor the participants knew which of the five treatment groups the participants were in. Participants received treatment for 24 weeks. Participants were evaluated at the start of the study and at weeks 4, 8, 16, and 24 and closely monitored for improvement of their symptoms as well as for any possible adverse reactions to the study agents. X-rays documented each participant's diagnosis of osteoarthritis. Participants were also stratified into two pain subgroups--mild pain 1,229 participants (78 percent) and moderate-to-severe pain 354 participants (22 percent).
The primary outcome of the study was defined as at least a 20 percent reduction in pain at 24 weeks. All participants had the option to use up to 4000 mg of acetaminophen, as needed, to control pain from osteoarthritis throughout the study, except for the 24 hours prior to having their knee assessed. Acetaminophen use was low: on average, participants used fewer than two 500 mg tablets per day.
Source: NCCAM, National Institutes of Health, [nccam.nih.gov/research/results/gait]