Effective factors on Auditory Brainstem Response test in Newborns

Promotion of community health careis one of the major health and treatment policies. In this regard, prevention is considered the primary, most important and effective level of health care. Given the high prevalence of congenital (sensorineural) hearing loss (nearly 1/1000 to 3/1000 of live births) large numbers of neonates with congenital hearing loss will be born annually. Hearing loss will cause adverse effects on social, cognitive and speech development of these children. Therefore, early, even neonatal, diagnosis and treatment of hearing loss has been recommended in order to prevent such complications. This study has been conducted with the aim of hearing screening of the newborns and evaluating the effective factors on Auditory Brainstem Response (ABR) test. In this descriptive study all included newborns were examined by TEOAE test during first week after birth. The result of the test was interpreted as “Pass” or “Refer”. In case of “Refer”, the test was repeated 3 weeks later. In neonates with the test result of “refer” in the second step, the ABR was done.The following risk factors were evaluated: 1) History of NICU admission for more than 48 hours 2) History of neonatal exchange transfusion 3) Family history of hearing deficiency 4) Birth weight 5) Administration of aminoglycosides in neonatal period. Of the total5850 evaluated newborns, 5148 (88%) gained criteria of “Pass” in first step of the test, while 702 cases (12%) were “Referred” to the second step and 468(8%) had impaired ABRtest. Related risk factors were evaluated in neonates with the abnormal OAE test or in those with the result of “Refer”. This showed that: 1) History of NICU admission for more than 48 hours was positive in 4.8% of normal newborns but in 55% of neonates with abnormal ABR test, and the difference was significant (P<0.001). 2) Family history of hearing deficiency was positive in 4.4% of normal newborns but 5.9% of neonates with abnormal ABR test, so there was not a significant relation (P=0.191). 3) Low birth weight (<1500 gr) was found in 1.5% of normal newborns and 11.5% of neonates with abnormal ABR test, and the relation was statistically significant (P<0.001). 4) History of neonatal exchange transfusion was present in 2.8% of normal newborns but 2.1% of neonates with abnormal ABR test, so there was not a significant relation (P=0.563) 5) Administration of aminoglycosides in neonatal period was present in 2% of normal newborns but20% neonates with abnormal ABR test, which were significantly different (P<0.001). The results showed a significant relation between abnormal ABR test and history of NICU admission for more than 48 hours, low birth weightand administration of aminoglycosides in neonatal period. Because of high prevalence of congenital hearing loss and it’s adverse effects on child development, screening of hearing sense is recommend as soon as clinically possible after birth. In addition, paying attention to the related risk factors and particular focus on neonates with such risk factors seems beneficial. Among the four risk factors evaluated in this study, abnormal ABR test was significantly related with the history of NICU admission for more than 48 hours, low birth weight (<1500 gr),and administration of aminoglycosides in neonatal period. However the two risk factors of positive family history and history of neonatal exchange transfusion were not significantly related with hearing loss.