Results
The electronic database search revealed a total of 9032 studies. After
screening for suitability, 34 studies were included in the final
synthesis 23-56. The PRISMA flow diagram is depicted
in Figure 1 . Thirty-three studies (3994 neonates) and 31
studies (3783 neonates) were analysed for the primary outcomes of
treatment failure and requirement of mechanical ventilation,
respectively. The mean gestational age of the neonates was 31 weeks
(E-Figure 1). Five studies had enrolled neonates who had
already received surfactant prior to randomisation. The time cuts-offs
for treatment failure and mechanical ventilation was within the first 72
hours after randomisation for most of the included studies. The
characteristics of the included studies are given in Table 1 .