*2.6. Statistical Analysis*

Meta-analysis was performed only when there were at least three contrasts available for data synthesis. Risk ratios (RRs) with 95% confidence intervals (CIs) were calculated for dichotomous data, and the mean difference (MD) or standardized mean difference (SMD) along with corresponding 95% CIs were calculated for continuous outcomes. Heterogeneity was assessed using the Cochran Q statistic (*p* < 0.1) and measured with the *I* <sup>2</sup> statistic. Meta-analyses were conducted using a random-effects model regardless of heterogeneity. Two-sided *p* < 0.05 was considered statistically significant. We used Stata version 15 (Stata Corporation, College Station, TX, USA) for data analyses.
