Prevalence and independent risk factors for hearing impairment among very low birth weight infants

Background Although we've made big strides in perinatal and neonatal care, auditory handicap remains a serious complication in those who were born very premature. Objectives The aim was to determine the prevalence and analyze possible risk factors of hearing impairment in very-low-birth-weight (VLBW) infants. Materials and methods This was a retrospective study by reviewing medical records of all VLBW infants (BW ≤ 1500 g) admitted to NICU of Chang Gung Children's Hospital over 2 years period from Jan. 2010 to 2011. Brainstem auditory evoked potentials (BAEP) hearing screening was performed at 3 months postnatal corrective age and repeated if failed the 1st time, then refer to ENT doctor if BAEP confirmed abnormal. All VLBW infants examined for hearing impairment were included and data were retrieved retrospectively and analyzed for neonatal risk factors using logistic regression. Results Over the period, 309 VLBW infants were screened. Prevalence of uni- or bilateral hearing impairment was 3.9% (12/309; 95% CI 2.6–4.1). The mean corrective age on diagnosed of hearing impairment was 2.9 ± 1.1 (range 1–5) months. Mean gestational age was 27.9 weeks (SD 1.4) and mean birth weight was 1028 g (SD 180). By univariant analysis for hearing impairment, severe birth asphyxia, craniofacial anomalies, ventilator dependence, patent ductus arteriosus ligation, and use of postnatal ototoxins yielded good prediction of hearing impairment in this population. However, using multivariate analysis revealed that the only independent risk factors for hearing impairment were ototoxins (OR: 3.62; CI: 1.67–7.82), PDA ligation (OR: 4.96; CI: 2.34–10.52), craniofacial anomalies (OR: 3.42; CI: 1.70–6.88)and assisted prolonged use of oxygen at gestational age of >36 weeks (OR: 5.94; CI: 2.61–13.54). Conclusion The incidence of hearing impairment among VLBW infants was 3.9%. Prolonged supplemental oxygen use is a marker for predicting hearing impairment; this requires detailed analysis of the pathophysiologic features, to reduce the prevalence of hearing impairment.