Data synthesis and analysis
A meta-analysis was performed using the random-effects model with the
Mantel-Haenszel method using Review Manager (RevMan), version 5.4 (The
Nordic Cochran Center, The Cochrane Collaboration). The effect estimates
were reported as RRs and absolute risk differences (ARDs) with 95%
confidence intervals (95% CIs). Statistical significance was set at p
< 0.05. Heterogeneity was assessed by visual inspection of the
forest plot using the χ2-test (significant if
p<0.10) and I2 statistic (heterogeneity
considered significant if I2 > 40%).
Subgroup analyses by gestational age (<28 gestational weeks,
28-32 gestational weeks), respiratory support (invasive ventilation or
non-invasive ventilation), and age after birth (acute phase; 0-27 days,
chronic phase ≥ 28 days) were preplanned and performed.