Admission hypothermia, neonatal morbidity, and mortality: evaluation of a multicenter cohort of very low birth weight preterm infants according to relative performance of the center.

This prospective cohort study aimed to assess the association of admission hypothermia (AH) with death and/or major neonatal morbidities among very low birth weight (VLBW) preterm infants based on the relative performance of 20 centers of the Brazilian Network of Neonatal Research. This is a retrospective analysis of prospectively collected data using the database registry of the Brazilian Network on Neonatal Research. Center performance was defined by the relative mortality rate using conditional inference trees. A total of 4356 inborn singleton VLBW preterm infants born between January 2013 and December 2016 without malformations were included in this study. The centers were divided into two groups: G1 (with lower mortality rate) and G2 (with higher mortality rate). Crude and adjusted relative risks (RR) and 95% confidence intervals (95%CI) were estimated by simple and multiple log-binomial regression models. An AH rate of 53.7% (19.8-93.3%) was significantly associated with early neonatal death in G1 (adjusted RR 1.41, 95% CI 1.09-1.84) and G2 (adjusted RR 1.29, 95%CI 1.01-1.65) and with in-hospital death in G1 (adjusted RR 1.29, 95%CI 1.07-1.58). AH was significantly associated with a lower frequency of necrotizing enterocolitis (adjusted RR 0.58, 95%CI 38-0.88) in G2.Conclusion: AH significantly associated with early neonatal death regardless of the hospital performance. In G2, an unexpected protective association between AH and necrotizing enterocolitis was found, whereas the other morbidities assessed were not significantly associated with AH. What is Known: • Admission hypothermia is associated with early neonatal death. • The association of admission hypothermia with major neonatal morbidities has not been fully established. What is New: • Admission hypothermia was significantly associated with early neonatal and in-hospital death in centers with the lowest relative mortality rates. • Admission hypothermia was not associated with major neonatal morbidities and with in-hospital death but was found to be a protective factor against necrotizing colitis in centers with the highest relative mortality rates.