Data analysis
This meta-analysis was performed using Stata, release 14. All results were binary variables and were presented as summary risk ratios (RR) with 95% confidence intervals (CI). We calculated the summary RR and 95% CI by using a fixed effects model. A random effects model was used if the high heterogeneity19. The subgroup analysis was conducted according to study type (IST-DP, IPT-DP-4-6w, IPT-DP-8w, IPT-SP-4-6w, IPT-SP-8w).
The influence of study quality on results was assessed by sensitivity analysis. The extent of heterogeneity was interpreted by the total percentage of variation between the studies concerned, measured by theI 2 statistic. The I ² value was categorized as low if I ² was 0–25%, moderate if I ²was 25–50%, high if I ² was 50–90%. Additionally, Q-statistic was used to assess the presence of heterogeneity. PQ statistic≥0.05 was considered to indicate no significant heterogeneity among the included studies20.
The test of publication bias was not necessary because the included studies were less ten21.