2.3 Statistical analysis
Review Manager 5.3 (Cochrane, London, UK) was used to perform data analysis using random effects models. Statistical heterogeneity was assessed using the I2 statistic. Sensitivity analyses were conducted to identify potential heterogeneity by leaving out any study. Publication bias was evaluated by generating a funnel plot of the logarithm of effect size against the standard error for each trial.
P < 0.05 was considered statistically significant in all analyses.