We present dichotomous outcomes as odds ratios with 95% confidence intervals (CI) and combined this result from each study with the Mantel-Hanzel fixed-effect method. Continuous outcomes were compared with the inverse- variance method to obtain the mean difference and CI with a fixed-effect model. Heterogeneity was assessed with the Chi-squared test, and I2 was checked among studies. If there was no heterogeneity (I2 = 0%), a fixed-effect model was used to pool the data. If the level of heterogeneity was acceptable (I2 between 0% and 40%), a meta-analysis was performed with a random-effect model.