Efficacy of Botulinum Toxin Type A in Improving Scar Quality and Wound Healing: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background: Botulinum toxin type A-induced "chemoimmobilization" has long been utilized for improved scar quality and wound healing; however, current evidence is limited to small studies, and evidence-based information is inadequate to make well-informed decisions. Objectives: The purpose of this study was to evaluate the efficacy of botulinum toxin type A (BTA) to improve scars and wound healing. Methods: The authors searched databases, including Pubmed, Embase, and Cochrane Library, to identify randomized clinical trials (RCTs) that compared outcomes of surgical scars and wounds treated with BTA vs those treated with blank or placebo controls. The Visual Analog Scale, Vancouver Scar Score, scar width, and reported patient satisfaction were utilized in evaluating outcomes. Adverse events were also recorded. Results: Eleven RCTs involved a total of 486 cases (374 patients). Quantitative synthesis suggested that compared with the control group, patients in the BTA treatment group had significantly higher Visual Analog Scale scores (mean difference [MD] = 1.30, 95% confidence interval [CI]: 1.05 to 1.55), lower Vancouver Scar Scores (MD = -1.62, 95% CI: -2.49 to -0.75, P = 0.0003), and thinner scars (MD = -0.15, 95% CI: -0.20 to -0.11, P < 0.00001). Patient satisfaction was higher in the BTA group than in the control group (risk ratio: 1.25, 95% CI: 1.06 to 1.49, P = 0.01). Trivial adverse events were reported. Conclusions: This meta-analysis of RCTs provides reliable evidence that BTA injection is superior to placebo or blank control group in improving scar quality and wound healing in the face and neck for Asians, and negative outcomes for BTA treatment in these patients include only trivial adverse events. However, inadequate evidence supports utilization of BTA in Caucasians for primary surgical scars or for scars in locations other than the face and neck. Further studies on the standardized injection regimen and technique of BTA are warranted for clinical practice.