Safety of Botulinum Toxin A Injections for Facial Rejuvenation: A Meta-Analysis of 9,669 Patients.

[PURPOSE] To quantitatively evaluate safety profile for botulinum toxin A (BTX-A) injections among patients undergoing treatment for cosmetic indications is produced, with special attention to clinically relevant covariates and their relative impact on safety.

[METHODS] A systematic literature search was performed using PubMed (1996-January 2020) and Embase (1947-January 2020) to identify all randomized controlled trials (RCTs) that reported safety data for patients receiving BTX-A for cosmetic indications compared to placebo. A meta-analysis was performed to determine pooled risk ratios (RR) for treatment-related adverse events (TRAEs) and for specific adverse events. Meta-regression and additional analyses were performed for significant and/or clinically relevant covariates.

[RESULTS] Following the review of 8,690 studies, 32 RCTs involving 9,669 patients were included. The pooled RR of any TRAE occurring after BTX-A injection compared to placebo injection was 1.53 (95% CI, 1.33-1.77; p < 0.001). Statistically significant covariates included individual injection volume and total injection volume. The type of BTX-A formulation, treatment site, total BTX-A units, and BTX-A units per injection were not significant. Specific adverse events more likely to occur following BTX-A injection rather than placebo injection included eyelid/eyebrow malposition (RR 3.55; p < 0.001), facial paresis (RR 2.42; p = 0.316), and headache (RR 1.45; p = 0.003). Injection site reactions and injection site bruising occurred at similar rates in both groups.

[CONCLUSIONS] The overall safety profile of BTX-A is acceptable and consistent with previous publications. The authors' additional analyses provide a relative comparison of the impact of various treatment parameters on safety.