Comparative Study of Hearing Impairment Among Healthy and Intensive Care Unit Neonates in Mashhad, North East Iran

Introduction: According to World Health Organization (WHO) 2001 statistics, hearing disorders are the most common congenital disease, and the incidence rate among high-risk newborns is as much as ten times as high as that in healthy neonates. However, 78% of screening test failures are well-baby nursery babies. The Joint Committee on Infants' Hearing (JCIH) has emphasized the importance of early diagnosis and treatment in neonates with hearing impairments in order to preserve their maximum linguistic skills. The aim of our study was to compare the prevalence of hearing loss among babies in the neonatal intensive care unit (NICU) and the rooming-in unit (RIU).

Materials And Methods: Neonates born in three hospitals in Mashhad between 2008 to 2010 were studied prospectively and screened for auditory disorders using the oto acoustic emission (OAE) test at the time of discharge and 3 weeks later. To confirm hearing loss, the auditory steady state response (ASSR) test was used among those participants who failed both OAE tests.

Results: Two-thousand and sixty-three neonates from the NICU were screened and compared with a control group consisting of 8,724 neonates from the RIU or the well-baby nursery. At the end of the study, hearing impairment as confirmed by failure in the ASSR test was diagnosed in 31 neonates (26 in the control group [0.30%] and five in the NICU group [1.94%]).

Conclusion: In our study, the prevalence of hearing disorders among NICU neonates was 6.5-times greater than that among babies from the RIU or well-baby unit. This observation demonstrates the importance of universal screening programs particularly for high-risk population neonates.