Statistical analysis
Revman 5.3 software (Review Manager (RevMan), The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen) and Stata 14.0 software (StataCorp, College Station, TX, USA) were used to statistical analysis. Categorical data were combined by relative risk (RR) or odds ratio (OR), and quantitative data were combined by weighted mean difference (WMD) or standardized mean difference (SMD). Heterogeneity was tested by 