Birthweight and gestational age as modifiers of rehospitalization after NICU admission

Objective: To assess interaction effects between gestational age and birth weight on 30-day unplanned hospital readmission following discharge from the neonatal intensive care unit (NICU). To assess the relationship between gestational age and day of life (DOL) on neonatal intensive care unit (NICU) admission and the risk for 30-day unplanned hospital readmission (UHR). Methods: Retrospective study using the study site’s Children's Hospitals Neonatal Database (CHND) and electronic health records were used. Population included patients discharged from a NICU between January 2017 and March 2020. Variables encompassing demographics, gestational age, birth weight, medications, maternal data, and surgical procedures were controlled for. A statistical interaction between gestational age and DOL birth weight was tested for statistical significance. Results: 2,307 neonates were included, with 7.2% readmitted within 30 days of discharge. Statistical interaction between birth weight and gestational age was statistically significant, indicating that the odds of readmission amongst low-birth-weight premature patients increases with increasing gestational age, while it decreases with increasing gestational age amongst their normal or high birth weight peers. Conclusions: The effect of gestational age on odds of hospital readmission is dependent on birth weight.