Because of the publicity it has received in the media, glucosamine has become one of the most commonly used dietary supplements in the United States. Several studies sponsored by the supplement industry have suggested that glucosamine is effective in the management of osteoarthritis. A meta-analysis of early trials of this supplement discovered methodologic problems and possible publication bias, and in two recent independent trials, glucosamine therapy was found to be ineffective for osteoarthritis. Because trials of osteoarthritis treatment are burdensome and costly, McAlindon and associates developed a method for performing clinical trials using the Internet, and used this technique to evaluate the safety and effectiveness of glucosamine in the management of knee osteoarthritis.
The authors conducted a double-blind, placebo-controlled study of glucosamine in patients with osteoarthritis. The patients were recruited and followed using the Internet. Inclusion criteria were: 45 years or older; osteoarthritis of at least one knee, as established by radiography or magnetic resonance imaging; and pain, aching, or stiffness in either knee on most days. Exclusion criteria were: a knee injection within 60 days of the study; arthroplasty of the knee; and current use of glucosamine, chondroitin, or other agents that claim to have osteoarthritis structure-modifying properties. The patients were randomized to receive 1.5 g of glucosamine or placebo daily for 12 weeks. The main outcome measure was the pain subscale on the Western Ontario and McMaster Universities Osteoarthritis Index, which includes three subscales (pain, stiffness, and function) and generates scores for each subscale as well as an overall score. Analgesia use and adverse events also were recorded.
There were 205 patients enrolled in the study. The groups receiving glucosamine and placebo did not differ with regard to pain scores, stiffness, physical function, overall scores on the Index, and analgesic use. No significant differences were noted between the patients who received glucosamine and those who received placebo when the groups were stratified for severity of osteoarthritis, glucosamine product, use of a nonsteroidal anti-inflammatory drug, and the exclusion of opiate use. The groups had similar numbers and types of adverse events recorded during the study.
The authors conclude that glucosamine, while appearing to be safe, is no more effective than placebo in treating the symptoms of knee osteoarthritis. They add that Internet-based clinical trials may provide a quick and efficient method for further studies on the effectiveness of glucosamine products.