Purpose Hospital length of stay (LOS) is important to administrators and families of neonates admitted to the intensive care unit (NICU). A prediction model for NICU LOS was developed using as predictors birth weight, gestational age, and two severity of illness tools, the Score for Neonatal Acute Physiology (SNAPPE) and the Morbidity Assessment Index for Newborns (MAIN). Materials and Methods Consecutive admissions (n=293) to a New England regional level III NICU were retrospectively collected in 1999. Multiple predictive models were compared for complexity and goodness-of-fit, coefficient of determination (R2) and predictive error. The optimal model was validated prospectively with consecutive admissions (n=615) in 2002. Observed and expected LOS was compared. Results LOS was longer in the 2002 cohort than the 1999 cohort, without differences in birth weight, gestational age, MAIN or SNAPPE. The MAIN models had best AIC, highest R2 (0.786) and lowest predictive error. The best SNAPPE model underestimated LOS, with substantial variability, yet was fairly well calibrated by birthweight category. Conclusions Length of stay prediction is improved by accounting for severity of illness in the first week of life beyond factors known at birth. Prospective validation of both MAIN and SNAPPE models is warranted.

Objectives To assess the influence of clinical status on the association between total plasma bilirubin and unbound bilirubin on death or adverse neurodevelopmental outcomes at 18–22 months corrected age in extremely low birth weight infants. Method Total plasma biirubin and unbound biirubin were measured in 1,101 extremely low birth weight infants at 5±1 day of age. Clinical criteria were used to classify infants as clinically stable or unstable. Survivors were examined at 18–22 months corrected age by certified examiners. Outcome variables were death or neurodevelopmental impairment, death or cerebral palsy, death or hearing loss, and death prior to follow-up. For all outcomes, the interaction between bilirubin variables and clinical status was assessed in logistic regression analyses adjusted for multiple risk factors. Results Regardless of clinical status, an increasing level of unbound bilirubin was associated with higher rates of death or neurodevelopmental impairment, death or cerebral palsy, death or hearing loss and death before follow-up. Total plasma bilirubin values were directly associated with death or neurodevelopmental impairment, death or cerebral palsy, death or hearing loss, and death before follow-up in unstable infants, but not in stable infants. An inverse association between total plasma bilirubin and death or cerebral palsy was found in stable infants. Conclusions In extremely low birth weight infants, clinical status at 5 days of age affects the association between total plasma and unbound bilirubin and death or adverse neurodevelopmental outcomes at 18–22 months of corrected age. An increasing level of UB is associated a higher risk of death or adverse neurodevelopmental outcomes regardless of clinical status. Increasing levels of total plasma bilirubin are directly associated with increasing risk of death or adverse neurodevelopmental outcomes in unstable, but not in stable infants.