Efficacies of different preparations of glucosamine for the treatment of osteoarthritis: a meta-analysis of randomised, double-blind, placebo-controlled trials

Objective To determine the efficacies of different preparations of glucosamine for the treatment of osteoarthritis (OA). Methods Systematic searches of the bibliographic databases Medline, Embase, the Cochrane Central Register of Controlled Trials and the Cochrane Database of Systematic Reviews for randomised, double-blind, placebo-controlled trials (RCTs) concerning glucosamine treatment of OA. Effect size (ES) was estimated using Cohen's standardised mean difference. Consistency was evaluated via the I2 index. Results Nineteen trials (3159 patients) contributed to the meta-analysis, revealing a large degree of inconsistency among the trials in terms of pain-reduction outcome: the combined ES in glucosamine sulphate (GS) trials was 0.22 [95% confidence intervals (CI) 0.48, 0.04], I2 was 82.3%. The combined ES in glucosamine hydrochloride (GH) trials was 0.03 (95% CI 0.14, 0.08), with an absence of heterogeneity. No treatment ES was observed [0.38 (95% CI 0.99, 0.23)] favouring GS in trials of less than 24weeks duration and the I2 remained high (I2=88.5%). No significant treatment ES 0.09 (95% CI 0.21, 0.03) was observed in trials of more than 24weeks duration compared with placebo, with a heterogeneity of zero. In terms of function-modifying outcomes, GS showed no significant effect on Lequesne Index reduction vs. placebo in trials of less than 24weeks duration (ES 0.55 (95% CI 1.22, 0.11)) with a high degree of heterogeneity (I2=92.9%). Pooling data from studies with durations of more than 24weeks presented a significant combined ES of 0.36 (95% CI: 0.56, 0.17) with an absence of heterogeneity. No risk of publication bias could be detected using Egger test. Conclusions GH is ineffective for pain reduction in patients with knee OA. GS may have function-modifying effects in patients with knee OA when administered for more than 6months. However, it showed no pain-reduction benefits after 6months of therapy.