Porcine versus bovine surfactant therapy for RDS in preterm neonates: pragmatic meta-analysis and review of physiopathological plausibility of the effects on extra-pulmonary outcomes

BACKGROUND: While porcine seems to be superior to bovine surfactants in terms of respiratory outcomes, it is unclear if a surfactant can improve extra-pulmonary outcomes in preterm neonates with respiratory distress syndrome and if there is any physiopathological/biological mechanism linking surfactant therapy to these outcomes. We aim to fill these knowledge gaps. METHODS: Systematic and pragmatic review coupled with meta-analysis of randomized controlled trials of bovine or porcine surfactants administered to treat RDS in preterm neonates; common extra-pulmonary neonatal intensive care outcomes were considered. As additional analysis, animal or human translational studies about mechanisms linking surfactant replacement to extra-pulmonary neonatal outcomes were also systematically reviewed. RESULTS: Porcine surfactant is associated with lower incidence of patent ductus arteriosus (OR:0.655; 95%CI:0.460–0.931); p = 0.018; 12 trials; 1472 patients); prenatal steroids (coeff.:-0.009, 95%CI:-0.03–0.009, p = 0.323) and gestational age (coeff.:0.079, 95%CI:-0.18–0.34, p = 0.554) did not influence this effect size. No significant differences were found between porcine and bovine surfactants on neonatal intensive care unit length of stay (mean difference (days):-2.977; 95%CI:-6.659–0.705; p = 0.113; 8 trials; 855 patients), intra-ventricular hemorrhage of any grade (OR:0.860; 95%CI:0.648–1.139); p = 0.293; 15 trials; 1703 patients), severe intra-ventricular hemorrhage (OR:0.852; 95%CI:0.624–1.163); p = 0.313; 15 trials; 1672 patients), necrotizing entero-colitis (OR:1.190; 95%CI:0.785–1.803); p = 0.412; 9 trials; 1097 patients) and retinopathy of prematurity (OR:0.801; 95%CI:0.480–1.337); p = 0.396; 10 trials; 962 patients). CONCLUSIONS: Physiopathological mechanisms explaining the effect of surfactant have been found for patent ductus arteriosus only, while they are lacking for all other endpoints. Porcine surfactant is associated with lower incidence of PDA than bovine surfactants. As there are no differences in terms of other extra-pulmonary outcomes and no physiopathological plausibility, these endpoints should not be used in future trials. REGISTRATION: PROSPERO n.CRD42018100906.