Data synthesis and analysis
In present article, analyses were conducted using STATA software version 12.0 (Stata Corp, College Station, TX). Weighted mean difference (WMD) and confidence interval (CI) of 95% were calculated for continuous outcomes, while pooled odds ratios (ORs) and confidence interval (CI) of 95% were estimated for dichotomous outcomes. We used I2 statistics to examine the heterogeneity of the studies. The value of I2 was reported as a percentage of total variation across studies, where I2> 50% indicates considerable heterogeneity. If no heterogeneity was found between studies, a fixed-effect model was used for meta-analysis. If there was significant heterogeneity among studies, a random-effects model was utilized for the analysis. Sensitivity analysis was performed by deleting each study sequentially to assess the robustness of the combined estimates. Funnel plots, Begg’s and Egger’s test were used to evaluate and test publication bias, respectively.