Prevalence of Hearing Impairment in Primary School Children
Results from a 30 Year Study of Annual Hearing Examinations in Sendai City
2000 Volume 43 Issue 2 Pages 141-147
Details
2000 Volume 43 Issue 2 Pages 141-147
For 30 years (1968-1997), we have investigated the changes in the prevalence of hearing impairment in primary school children in Sendai City and have obtained the following results:
1) The number of subjects increased gradually until 1981, and then decreased from 1982 in response to a remarkable population reduction of 0-14 years old children in Japan.
2) The prevalence of hearing impaired children rapidly decreased yearly from a peak of 1.94% in 1972. Subsequently, it was less than 1.0% in 1979, less than 0.5% in 1991, and was a little over 0.4% since 1994. This reduction is mainly attributed to the eminent decrease of a conductive hearing loss produced by secretory otitis media and chronic otitis media.
Sensorineural hearing loss also had decreased slowly from 0.6% in 1972 and was 0.22-0.26% after 1989.
3) Sensorineural and conductive hearing losses were more frequently found among boys than girls, and were more commonly unilateral than bilateral.
4) The percentage of children suffering from severe unilateral sensorineural hearing loss had been decreasing gradually from 0.1% before 1988 to 0.04%.
5) The prevalence of impaired hearing due to secretory otitis media has decreased, but it still remains the leading cause accounting for 50-60% of all conductive hearing losses.
