Effect modification of late surfactant treatment by patent ductus arteriosus status in ventilated preterm infants: a secondary analysis of a randomized clinical trial

OBJECTIVE: To evaluate whether the effect of late surfactant is modified by patent ductus arteriosus (PDA) status with respect to survival without bronchopulmonary dysplasia (BPD) in ventilated infants born <28 weeks' gestation. METHODS: Secondary analysis of the Trial of Late Surfactant (TOLSURF). A formal test of interaction between PDA presence and late surfactant, with respect to survival without BPD at 36 and 40 weeks' postmenstrual age (PMA), was performed. PDA presence was defined by PDA treatment, either medical or a ligation (definition A), or PDA ligation (definition B), during or after late surfactant administration. RESULTS: All 511 infants were included. No interaction was detected between a PDA and late surfactant for survival without BPD at 36 weeks' PMA (definition A: p = 0.41; definition B: p = 0.33), or at 40 weeks' PMA (definition A: p = 0.84; definition B: p = 0.42). CONCLUSION: PDA presence did not modify the effect of late surfactant for survival without BPD.