The Hassan Neonatal Morbidity Composite Scale and Neonatal Length of Stay-A Validation Study

Obstetric studies often report neonatal morbidity as a composite score. Composite scores can simplify data analysis when multiple outcomes of interest are present and allows researchers to conduct smaller, more manageable trials. The Hassan scale is a neonatal morbidity composite scale that assigns high scores to infants with multiple morbidities and low scores to infants without or with single morbidities. The objective of this study was to validate the association between scores on the Hassan scale and neonatal intensive care unit (NICU) length of stay STUDY DESIGN:  We conducted a cohort study of all infants born between 22 and 36^6/7 weeks' gestation and cared for within 419 neonatal units in the Pediatrix Medical Group between 1997 and 2018. Each infant was assigned a Hassan's score based on the number of neonatal morbidity events that occurred during the delivery hospitalization. The association between Hassan's scores and neonatal length of stay was evaluated using linear regression. Multivariable models were constructed to determine if the Hassan score was independently associated with neonatal length of stay.

There were 760,037 infants included. The median (interquartile range [IQR]) gestational age of delivery was 34 (31, 35) weeks and the median (IQR) birth weight at delivery was 2,000 (1,503, 2,430) g. The median length of stay for infants discharged home was 17 (10-33) days. A Hassan's score was able to be assigned to 699,206 (92%) patients. Neonatal morbidities included in the Hassan scale were more common among infants born earlier in gestation. On adjusted analysis, the Hassan scale was found to be independently associated with neonatal length of stay (p < 0.001, coefficient = 10.4 days [95% confidence interval (CI): 10.3, 10.4 days]) with higher scores associated with longer lengths of stay.

The Hassan scale, more than a binary composite score, is able to differentiate preterm infants with prolonged hospitalizations from those with short hospitalizations.

· The Hassan scale is an independent predictor of neonatal length of stay.. · Classification of infants based on number of morbidities correlates with neonatal length of stay.. · The Hassan scale provided better discrimination than binary composite morbidity scores.. · The Hassan scale may be an economic predictor of health-related costs..