RESUMO
OBJECTIVE: To examine the association of nursing overtime, nursing provision and unit occupancy rate with medical incident rates in the neonatal intensive care unit (NICU) and the risk of mortality or major morbidity among very preterm infants. STUDY DESIGN: Single center retrospective cohort study of infants born within 23 to 29 weeks of gestational age or birth weight <1000 g admitted at a 56 bed, level III NICU. Nursing overtime ratios (nursing overtime hours/total nursing hours), nursing provision ratios (nursing hours/recommended nursing hours based on patient dependency categories) and unit occupancy rates were pooled for all shifts during NICU hospitalization of each infant. Log-binomial models assessed their association with the composite outcome (mortality or major morbidity). RESULTS: Of the 257 infants that met the inclusion criteria, 131 (51%) developed the composite outcome. In the adjusted multivariable analyses, high (>3.4%) relative to low nursing overtime ratios (⩽3.4%) were not associated with the composite outcome (relative risk (RR): 0.93; 95% confidence interval (CI): 0.86 to 1.02). High nursing provision ratios (>1) were associated with a lower risk of the composite outcome relative to low ones (⩽1) (RR: 0.81; 95% CI: 0.74 to 0.90). NICU occupancy rates were not associated with the composite outcome (RR: 0.98; 95% CI: 0.89 to 1.07, high (>100%) vs low (⩽100%)). Days with high nursing provision ratios (>1) were also associated with lower risk of having medical incidents (RR: 0.91; 95% CI: 0.82 to 0.99). CONCLUSION: High nursing provision ratio during NICU hospitalization is associated with a lower risk of a composite adverse outcome in very preterm infants.