What we talk about when we talk about NICUs: infants' acuity and nurse staffing

Organizational features of neonatal intensive care influence the care of sick neonates. We estimated the acuity-adjusted nurse-to-patient ratio (NPR) in a national sample of Italian NICUs and factors influencing it.

Twelve monthly cross-sectional surveys were prospectively carried out in 63 NICUs. Number and acuity of infants, and number of nurses were recorded. Infants' acuity was assessed by Rogowki's 2013 and British Association for Perinatal Medicine 2001 classifications.

We collected 702 reports regarding 11 082 infants. Non-intensive infants represented about 75% of NICU residents. Very preterm infants (<1501 g birth weight or <30 weeks gestation) represented 10.8% of admissions, but 44% of all infants surveyed. Average acuity-adjusted NPR was 0.31 (interquartile range 0.28-0.38); NPR depended on case-mix (proportion of intensive infants), size of the unit (larger units had a lower NPR) and was higher during morning shifts (+18%). Clustering on hospitals, reflecting shared components within each hospital, explained 47% of the variability of NPR.

The majority of infants cared for in NICUs are not intensive. NPR is influenced by acuity of infants, size of units, shifts, but is largely due to other unobserved hospital-related organizational features.