Epidemiology of permanent childhood hearing impairment in Estonia, 1985-1990

This paper describes a retrospective study of permanent childhood hearing i mpairment (PCHI) greater than or equal to 40 dB HL in the better ear in chi ldren born between 1985 and 1990 and resident in Estonia. The prevalence ra te of all permanent hearing impairment for the birth cohort 1985-1990 was 1 72 (95 per cent (CI 151-194) per 100,000 live births and that of congenital impairment was 152 (CI 134-170) per 100,000. For the congenitally-impaired children, ii per cent had stayed in a neonatal intensive care unit for 48 hours or more, 2 per cent had a craniofacial abnormality, and 31 per cent h ad a family history of PCHI. As for aetiology, hereditary causes were stare d most frequently in 36 per cent of all of the cases of PCHI. The aetiology remained unknown in 34 per cent of cases. Additional disabilities were fou nd in 23 per cent of all cases. Specific syndromes were recognized in 2 per cent of hereditary cases. The mean age at the confirmation of hearing impa irment was 46.4 months and at hearing aid fitting 57.0 months. The results were compared with other European studies, particularly the Trent study.