Meta-analysis of efficacy of pressure therapy in treating patients with hypertrophic scars

Objective To systematically evaluate the efficacy of pressure therapy in treating patients with hypertrophic scars by meta-analysis. Methods Databases including PubMed, Embase, Web of Science, and Cochrane Library were retrieved with the search terms"hypertrophic scar, hyperplastic scar, HTS, pressure therapy, pressure treatment, and the Chinese Journals Full-text Database was retrieved with the search terms in Chinese version"增生性瘢痕,瘢痕增生,肥厚性瘢痕,压力治疗,压力疗法"to obtain the publicly published randomized controlled trials about pressure therapy in the treatment of patients with hypertrophic scar from the establishment of each database to July 2017. The measurement indexes included the effective ratio, Vancouver Scar Scale (VSS) score, scar vascularity, scar hardness, scar pigment, scar thickness, and value of scar color (brightness, red, and yellow). RevMan 5.3 and Stata 12.0 statistical software were used to conduct a meta-analysis of eligible studies. Results A total of 667 hypertrophic scar patients were enrolled in 11 articles, including 362 patients in pressure therapy group who received pressure treatment and 305 patients in untreated group who received no treatment. The bias risks of the 11 studies included were uncertain. Compared with those of untreated group, the effective ratio of patients in pressure therapy group was significantly increased, with the relative risk of 5.98 (95% confidence interval=1.83-19.46, P<0.01); the VSS score and scar vascularity of patients in pressure therapy group were obviously decreased, with weighted mean differences of -2.24 and -0.66 respectively (95% confidence interval=-4.16--0.33, -1.21--0.12, P<0.05); the scar hardness, scar pigment, scar thickness, and value of scar color (brightness, red, and yellow) of patients in pressure therapy group were not changed obviously (P≥0.05). Significant heterogeneity existed in the included studies of the effective ratio, VSS score, scar vascularity, scar hardness, scar pigment, and scar thickness, P<0.01, I²=90%, 87%, 80%, 93%, 86%, 94%. Pressure range might be the heterogeneity source of effective ratio, and pressure clothing combined with pressure pad therapy might be a heterogeneous source of VSS score. Sensitivity analysis showed that the combined effect size results were stable in the effective ratio and scar pigment, but not stable in the VSS score, scar thickness, scar hardness, and scar vascularity. There was no publication bias in the effective ratio, VSS score, scar hardness, scar pigment, and scar vascularity (P>0.1), while there was publication bias in the scar thickness (95% confidence interval=-19.77--3.30, P<0.1). Conclusions Compared with patients without treatment, in the treatment of hypertrophic scars, pressure therapy can obviously increase the effective ratio, reduce the VSS score and scar vascularity, but can not obviously improve the scar hardness, scar pigment, scar thickness, and value of scar color (brightness, red, and yellow).