Identification of neonatal hearing impairment: Characteristics of infants in the neonatal intensive care unit and well-baby nursery

Objective: The objective of this study was to describe the demographic data , medical status, and incidence of risk factors for hearing impairment in t he neonatal intensive care unit (NICU) and well-baby populations in a multi center prospective study designed to assess neonatal hearing impairment and to evaluate factors that might affect neonatal hearing test performance. Design: This was a prospective multicenter study funded by the National Ins titutes of Health-National Institute on Deafness and Other Communication Di sorders to evaluate the effectiveness of auditory brain stem response, tran sient evoked otoacoustic emissions, and distortion product otoacoustic emis sions for newborn hearing screening. Research staff at each site obtained i nformed consent and detailed demographic and medical data, including inform ation on established risk factors for hearing loss on 4478 high-risk infant s cared for in the NICU, 2348 infants from the well-baby nurseries with no risk factor, and 353 infants from the well-baby nurseries with risk factors . For follow-up purposes the sample was divided further to include a subgro up called selects. Selects were either infants from the well-baby nursery w ho had an established risk factor for hearing impairment (N = 353) or did n ot pass the neonatal hearing screen protocol (N = 80). In this study, we fo cus on the distribution of infants by nursery and risk factors only. Partic ular effort was made to enroll infants with risk factors for hearing loss i n both the NICU and well-baby nurseries. Descriptive analyses are used to d escribe characteristics of this sample. Results: All 10 of the risk factors established by the Joint Committee on I nfant Hearing in 1994 were identified in the NICU population. The four most common were ototoxic medications (44.4%), very low birth weight (17.8%), a ssisted ventilation > 5 days (16.4%), and low Apgar scores at 1 or 5 min (1 3.9%). In contrast, only six risk. factors were present in the well-baby nu rseries: family history (6.6%), craniofacial abnormalities (3.4%), low Apga r scores (2.8%), syndromes (0.5%), ototoxic medications (0.2%), and congeni tal infection (0.1%). Conclusion: These descriptive risk factor data reflect both the newborn pop ulations at the study sites and the bias for enrolling infants at risk for hearing loss. The high-risk NICU sample reflects the characteristics typica lly found in graduates of the NICU. The data summarized in this study will be used to assess the relationships between risk factor and hearing test ou tcome.