This meta-analysis evaluated 25 randomized control trials which assessed the efficacy of glucosamine for pain due to osteoarthritis (OA), when compared to a placebo group. The study included a total of 3,458 patients who were assessed over short- (at least 4 weeks) or long-term (up to 3 years) periods. The purpose of the study was to determine factors which may account for inconsistencies between trials regarding the efficacy of glucosamine as a treatment for OA. Results indicated that the brand of glucosamine used, and the risk of bias of each study greatly affected variance in outcome results between studies.