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The epidemiology of childhood hearing impairment: factor relevant to planning of services
Insights
Neonatal intensive care unit (NICU) graduates face a significantly higher risk of hearing impairment, with 1 in 174 affected compared to 1 in 1278 non-NICU babies. NICU babies with hearing loss are also more likely to have other disabilities.
Area of Science:
- Audiology
- Pediatrics
- Public Health
Background:
- Hearing impairment affects 1 in 943 infants, with significant disparities between neonatal intensive care unit (NICU) graduates and other newborns.
- Congenital or progressive sensorineural/mixed hearing impairment is defined as 50 dB HL or greater in the better ear.
Purpose of the Study:
- To determine the prevalence of hearing impairment in infants, comparing NICU graduates with non-NICU babies.
- To investigate the association between NICU status, other disabilities, and acquired hearing impairments.
Main Methods:
- Retrospective analysis of infant hearing data from Nottingham District Health Authority (1983-1986).
- Comparison of hearing impairment rates between NICU graduates and non-NICU babies, adjusting for family history and syndromes.
- Assessment of the incidence of acquired hearing impairments and referral ages.
Main Results:
- NICU graduates have a 1 in 174 incidence of hearing impairment versus 1 in 1278 for non-NICU babies.
- NICU babies with hearing impairment have an 8.7:1 odds ratio for co-occurring disabilities.
- Acquired impairments account for 9% of cases by age 3, and 20% of severe cases (≥95 dB HL) at the Children's Hearing Assessment Centre.
Conclusions:
- Infants in the NICU are at substantially higher risk for hearing impairment and associated disabilities.
- Early identification and intervention are crucial, with mean referral ages of 8 months for severe congenital hearing impairments.
Abstract:
In the Nottingham District Health Authority we found that one in 943 babies born between 1983-1986 have a sensorineural or mixed hearing impairment (at 50 dB HL or greater in the better ear averaged over the frequencies 0.5, 1, 2, 4 kHz) that is either congenital or progressive in nature. If this figure is broken down between non-neonatal intensive care unit babies and neonatal intensive care unit (NICU) graduates, we find that one in 174 NICU graduates have a hearing impairment compared with one in 1278 non-NICU babies. Excluding from the non-NICU baby population those with a known family history of hearing impairment, and those with a known relevant syndrome at birth, there is a 10.2 to 1 odds ratio for babies in NICU to have such hearing impairments compared to this restricted 'normal' baby population. In addition NICU babies with a hearing impairment were considerably more likely to have another disability (odds ratio 8.7 to 1). Acquired sensorineural or mixed impairments comprised about 9% of the children with impairments by 3 years of age. Twenty per cent of the patients seen at the Children's Hearing Assessment Centre (CHAC) with better-ear impairment of 95 dB HL or greater had acquired hearing impairments. The mean age of referral for congenital hearing impairments was found to be a function of severity and NICU status. For children with better-ear hearing impairments of 80 dB HL or greater, the mean and median ages of referral were both 8 months (s.d. 4 months).