A National Institutes of Health study found that the supplements glucosamine and chondroitin alone and in combination relieve moderate-to-severe knee pain due to osteoarthritis. However, the supplements did not provide significant relief to patients within the overall study group or to those with mild pain, the researchers said.
The Glucosamine/chondroitin Arthritis Intervention Trial (GAIT) has taken five years to complete at a cost of about $14 million. Lead investigator Daniel O. Clegg, MD, of Salt Lake City, Utah, presented the GAIT results at the annual American College of Rheumatology (ACR) meeting.
Researchers designed the randomized controlled trial to “rigorously assess” the supplements’ safety and efficacy alone and in combination, they said. They randomized 1583 patients, of whom 1258 (80%) completed the study. All patients were older than 40 years; mean age was 58.6 years.
Patients were stratified into two subgroups: those with mild pain (125 to 300 mm on the Western Ontario and McMaster Osteoarthritis Index [WOMAC] pain scale) and those with moderate-to-severe pain (301 to 400 mm on the WOMAC scale) for at least six months. Patients also had radiographic evidence of knee OA (Kellgren-Lawrence grades 2 or 3).
Most patients (78%) fell into the mild pain group. Researchers evaluated patients at baseline and at four, eight, 16 and 24 weeks. The primary outcome measure was 20% improvement in WOMAC pain scores from baseline to the 24th week.
Researchers randomly assigned patients to double-blind groups for placebo, glucosamine alone (500 mg), chondroitin alone (400 mg), combined glucosamine and chondroitin (500 mg and 400 mg, respectively) and celecoxib (200 mg). All patients were allowed to take up to 4000 mg of acetaminophen daily as “rescue analgesia,” except within 24 hours of study visits.
Celecoxib (Celebrex, Pfizer Inc.) scored far better than placebo (70.1% vs. 60.1%, P=.008) in all the patient groups together. Combined glucosamine and chondroitin also scored higher than placebo; however, the difference was not significant (66.6% vs. 60.1, P=.09). Celecoxib also scored much higher than placebo among patients with mild pain (70.3% vs. 61.7%, P=.04). The combined supplements’ effect was not significant in the mild pain group.
The supplement combination scored far better than placebo (79.2% vs. 54.3%, P=.002) and highest overall among patients with moderate-to-severe pain. The difference between celecoxib and placebo was not significant in that group, the researchers said. Glucosamine alone and chondroitin alone performed better than placebo in all patient groups. However, the differences were not statistically significant, researchers said.
“While supplements were not effective in the overall patient population, combination [glucosamine and chondroitin] appears effective in patients with moderate-to-severe knee pain due to OA,” Clegg and his fellow researchers concluded. “The lack of response in patients with mild pain may be due in part to a floor effect, limiting ability to detect response. All study agents were well tolerated.”
For more information:
- Clegg DO, Reda DJ, Harris CL, et al. The efficacy of glucosamine and chondroitin sulfate in patients with painful knee osteoarthritis (OA): the Glucosamine/chondroitin Arthritis Intervention Trial (GAIT). #622. Presented at the American College of Rheumatology/ARHP Annual Scientific Meeting. Nov. 12-17, 2005. San Diego.