Performance profile of an outcome measure: morbidity assessment index for newborns

Few tools have been optimised for use over the entire spectrum of neonatal morbidity and standardised for use in perinatal population and community health studies. The objective of this study was to determine the performance profile of the recently developed morbidity assessment index for newborns (MAIN score). This score was designed as a discriminative index of morbidity for the entire population of babies delivered >28 weeks gestation without a major congenital anomaly.

MAIN score items were extracted retrospectively from the health records of 2892 consecutively born babies delivered beyond 28 weeks gestation in Edmonton area hospitals between June and December of 1999.

The mean MAIN score in the general newborn population was 70.3 (95% confidence intervals 64.2 to 76.4). With the MAIN score tool, 84.6% of newborns scored from 0 to 150 (no/minimal morbidity), 11.3% from 151 to 500 (mild), 3.1% from 501 to 800 (moderate), and 1% had >800 (severe) score. The MAIN score tool was sufficiently sensitive to detect significant effects of low gestational age, low birth weight, male sex, caesarean delivery, tertiary hospital delivery, twins/triplets, non-vertex presentation, prenatal illicit drug use, and medical complications of pregnancy.

The MAIN score fulfills the need for a simple, universal, yet sensitive and robust tool to provide a numerical index of early neonatal outcomes of prenatal care and adverse prenatal exposures in babies delivered beyond 28 weeks gestation. The performance of the MAIN score agrees well with the current medical awareness regarding the impact of adverse prenatal exposures on newborn morbidity.