Statistical Analysis

The effect estimates and 95% confidence intervals (CIs) from each eligible study were combined using the Mantel–Haenszel method²¹. Cochran’s Q was calculated, and statistical heterogeneity among the included studies was estimated using the I ² statistic. The four levels of heterogeneity were based on the value of I ²: (1) insignificant heterogeneity (I ²-value of 0% to 25%); (2) low heterogeneity (I ²-value of 26% to 50%); (3) moderate heterogeneity (I ²-value of 51% to 75%); and (4) high heterogeneity (I ²-value of 76% to 100%)²². Due to the high likelihood of between-study heterogeneity, a random-effects model was utilized rather than a fixed-effects model. Funnel plots were created to assess for publication bias. Statistical significance was determined to be P < 0.05. All statistical analyses were performed using Review Manager 5.3 software from the Cochrane Collaboration (London, UK).