Longitudinal pattern of factors causing hearing impairment in a school for the deaf

Abstract

This study describes the prevalence of children attending a school for the deaf in Copenhagen in 2002/2003 and the factors causing their hearing impairment (HI). In order to obtain longitudinal cross‐sectional information a comparison was made with causes evaluated in 1953, 1983 and 1993 (Arnvig, 1953; Holten and Parving, 1985; Parving and Hauch, 1994). In the school year 2002/2003 143 children attended the school. Information on 137 children was available. Data on the following parameters were evaluated: age, gender, hearing thresholds, factors causing the hearing impairment, additional handicaps and ethnicity. If the child suffered from a genetic HI, the mode of transmission was assessed whenever possible. The prevalence in children attending the school was found to be 0.05%, unchanged from 1983 and 1993. A significant increase in HI caused by genetic factors over the last 50 years was found ((29%(95%CI:24–32) in 1953 to 45%(95%CI:36–53) in 2003)). Furthermore, a rising frequency of cases of unknown aetiology was encountered ((21%(95%CI:17–24) in 1953, 36%(95%CI:28–45) in 2003)). The changing pattern of factors causing permanent HI should have implications for the service offered to children at schools for the deaf. Thus there is a need for improvement of the diagnostic process and genetic services and counselling should have high priority.

• aetiology of hearing impairment
• longitudinal changes
• permanent profound hearing impairment
• school for the deaf