In the pooled analysis, the surfactant was associated with a significantly lower use of rescue therapy (relative risk = 0.4, 95% confidence interval = 0.3-0.7, P < 0.0001). There was no evidence of heterogeneity (I 2 = 0%). This summary estimate should be interpreted with caution as only one trial reported a protocol for initiating rescue therapy. The decision to use a rescue therapy, particularly an open-label surfactant, may be influenced by knowledge of the patient's allocation; furthermore, only two trials reported blinded caregivers and the methods used to ensure blinding may not be adequate.