Epidemiology of the UK population of hearing-impaired children, including characteristics of those with and without cochlear implants--audiology, aetiology, comorbidity and affluence.

This study reports epidemiological data for 17,160 children with permanent bilateral hearing impairment >40 dB in the UK in the birth cohorts 1980-95 inclusive. Children were uniquely ascertained from notifications from professionals in health and education. Results indicate a changing aetiological profile over birth cohort. The percentage of unknown aetiologies and those of prenatal or postnatal origin have decreased, while syndromal and perinatal aetiologies have increased, with no change in genetic aetiologies. Nearly 30% of hearing-impaired children have another disability in addition to their hearing impairment. Children with cochlear implants are more likely than other profoundly impaired children to have a postnatal aetiology and less likely to have disabilities concerned with learning or cognition. A proxy measure of affluence indicates that significantly more profoundly impaired children in more affluent families receive cochlear implants than do those in less affluent families. These findings provide baseline data for the UK population and raise questions of widespread relevance for future research.