The impact of volume and neonatal level of care on outcomes of moderate and late preterm infants

Objective Evaluate the relationship of neonatal unit level of care (LOC) and volume with mortality or morbidity in moderate-late preterm (MLP) (32–36 weeks’ gestation) infants. Design Retrospective cohort study of 650,865 inborn MLP infants in 4976 hospitals-years using 2003–2015 linked administrative data from 4 states. Exposure was combined neonatal LOC and MLP annual volume. The primary outcome was death or morbidity (respiratory distress syndrome, severe intraventricular hemorrhage, necrotizing enterocolitis, sepsis, infection, pneumothorax, extreme length of stay) with components as secondary outcomes. Poisson regression models adjusted for patient characteristics with a random effect for unit were used. Results In adjusted models, high-volume level 2 units had a lower risk of the primary outcome compared to low-volume level 3 units (aIRR 0.90 [95% CI 0.83–0.98] vs. aIRR 1.13 [95% CI 1.03–1.24], p