Study of the prevalence of impaired hearing and its determinants in the city of Itajaí, Santa Catarina State, Brazil

The number of people with impaired hearing is increasing; knowing its magnitude is essential for public health. OBJECTIVE: To study the prevalence and determinants of impaired hearing in Itajaí/SC. METHODS: A population-based survey based on a World Health Organization protocol. Field research was carried out from July 2008 to 2011. Procedures for evaluating hearing in households: questionnaire, measurement of noise, otoscopy, pure tone audiometry at 1000, 2000, and 4000 Hz, tympanometry, and acoustic reflexes: individuals above 4 years; children under 4 years: evoked otoacoustic emissions (OAE), cocleo-palpebral reflex(CPR), tympanometry, and acoustic reflexes. In the elderly population a questionnaire of perception of hearing loss was applied. RESULTS: The study sample consisted of 379 individuals – 45.38% were males and 54.62% were females. Age-range: 11.34% up to 10 years; 64.39% 10 to 60 years, 24.27% over 60 years. Evaluation of the best hearing ear showed that 74.1% of residents had normal hearing, 18.9% had mild hearing loss, 5.1% had moderate hearing loss, 1.9% had severe hearing loss. Disabling impaired hearing was detected in 26 subjects: one child (otitis media); four adults (one otitis, one noise-induced, two idiopathic); 21 elderlies (presbyacusis). Of eight children under 4 years all presented CPR, three were normal examinations, two had absent OAE bilaterally, one had absent OAE in the right ear and one in the left ear. CONCLUSION: The prevalence of disabling impaired hearing in Itajaí was 7%; the highest prevalence was in the 50-year and above age group – the main cause was presbyacusis.