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].