Efficacy and Safety of Botulinum Toxin Type A in the Treatment of Glabellar Lines: A Meta-Analysis of Randomized, Placebo-Controlled, Double-Blind Trials.

BACKGROUND: The uses of botulinum toxin type A for facial aesthetic procedures have been reported in recently published studies. The authors systematically analyzed the prospective, randomized, controlled trials, which continue to expand. New efficacy data and endpoints regarding the safety of botulinum toxin type A injection for treating glabellar lines were analyzed. METHODS: The authors identified randomized controlled trials of botulinum toxin type A through searches of Ovid MEDLINE, PubMed, Elsevier, and the Cochrane Library from January of 2002 to November of 2014. The search terms included "botulinum toxin" and "glabellar lines." Only randomized, placebo-controlled, double-blind trials that used an injection dose of 20 units were included in the analysis. Safety was assessed by means of a meta-analysis of the number and frequency of adverse events. RESULTS: Seven studies involving 1474 subjects met inclusion criteria and qualified for meta-analysis. Overall, the pooled effective rate assessed by investigators in botulinum toxin type A treatment groups was significantly higher than that in controls (relative risk, 33.54; 95 percent CI, 18.65 to 60.33). The effective rate in treatment groups using a new endpoint was also higher than that in controls (relative risk, 99.04; 95 percent CI, 14.0 to 700.58). Subgroup analysis confirmed that botulinum toxin type A could improve the appearance of glabellar lines at rest (relative risk, 5.88; 95 percent CI, 3.49 to 9.91). There were no significant differences in the frequency of adverse events between the treatment and placebo groups in any of the studies. CONCLUSION: This meta-analysis shows that a single 20-unit dose of botulinum toxin type A is considered remarkably effective and safe for the treatment of glabellar lines. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.