2.6 Data extraction and analysis
Two investigators independently extracted data from the articles. We generated descriptive tables for population and study characteristics for all eligible studies to prepare for quantitative analysis. For each eligible study, we recorded study characteristics such as the first author, publication year, study design, duration of follow-up, sample size, and outcome measures. The size of the lesions, VAS score, mean age and BMI were also recorded as characteristics of the patients.
Analysis was performed with RevMan 5.4 (Cochrane collaboration). We synthesized the relative risk (RR) with a 95% confidence interval (CI) for dichotomous data and mean difference (MD) with a 95% CI for continuous data. The mean values were calculated using the median, sample size, and interquartile ranges if they were not described[18,19]. The I2 value was used to evaluate the heterogeneity between the included articles. An I2 statistic with a value greater than 50% indicated substantial heterogeneity between studies. To account for substantial heterogeneity, we used random-effects models [20].