Prevalence of permanent neonatal hearing impairment: systematic review and Bayesian meta-analysis.

Objective: To investigate the variance in reported prevalence rates of permanent neonatal hearing impairment (HI) worldwide. Design: A systematic review and meta-analysis was performed on reported prevalence rates of sensorineural and permanent conductive or mixed HI worse than 40 dB in neonates, detected as a result of a screening programme or audiometric study. Study sample: For meta-analysis, 35 articles were selected, 25 from high-income countries and 10 from middle-income countries according to the world bank classification system. Results: The prevalence rate of permanent uni- and bilateral HI worse than 40 dB in neonates varied from 1 to 6 per 1000, the overall prevalence was 2.21 per 1000 [1.71, 2.8]. In NICU populations the prevalence rate was higher with a larger fraction of bilateral cases. Although not significant, prevalence rates were slightly higher in Asia compared to Europe and the number of infants lost to follow-up appeared higher in countries with lower gross national income. Conclusion: Substantial variations exist in prevalence rates of neonatal permanent HI across countries and regions. There is a strong need for more data from low-income countries to identify demographic factors that account for this variability in reported prevalence rates. Reporting these data in a uniform way is advocated.