2.5 | Data analysis
Meta-analysis was performed by Review Manager 5.3 (The Cochrane Collaboration, Copenhagen, Denmark) and Stata 14.0 (Stata Corporation, College Station, TX, USA). Effect sizes computed for the analyses were presented as risk ratios (RR) with 95% confidence intervals (CI). The RR was not estimable when the events were zero in both groups. I2<50% was indicative of no heterogeneity, and the fixed effect model was adopted. By contrast, I2 >50% was indicative of heterogeneity, and the random effect model was applied after sensitivity analysis. Publication bias was assessed visually by funnel plots and then by Egger tests. P < .05 was considered statistically significant.