Neonatal risk factors and risk scores including auditory evoked responses

In a prospective study, 81 preterm infants and 25 healthy term infants were neurologically and neurophysiologically evaluated in the neonatal period. At 5-7 years of age the neurodevelopmental outcome was assessed. The validity and predictive value of the Neonatal Neurological Inventory (NNI) and the Neurobiological Risk Score (NBRS), including an additional gestational age factor (GAF) and an auditory evoked response factor (AERF) were assessed. Three of the 53 surviving preterm infants showed major neurological abnormalities at 5-7 years. Five infants showed neuropsychological abnormalities and 12 infants showed both neurological and neuropsychological abnormalities. An important subgroup of preterm infants could be identified as high-risk using the NNI and NBRS. The low sensitivity and negative predictive value resulted in a number of false-negative results. Logistic regression showed that intraventricular haemorrhage (IVH) and bilirubin levels contributed highly to the prediction of neurological outcome. For neuropsychological outcome these factors were IVH and assisted ventilation. Addition of the GAF and AERF as separate items to the NBRS did not affect the predictive power. Combined addition of the GAF and AERF showed improvement of both validity and predictive value.

This study shows that IVH, bilirubin and assisted ventilation contribute most to the validity and predictive value of the NBRS. Furthermore, regarding neurological outcome addition of a GAF in combination with an AERF resulted in a substantial improvement of the validity and predictive value. The shortcomings of the current neonatal risk scores require a careful interpretation of clinical perinatal data regarding the prediction of neurodevelopmental outcome in preterm infants.