Dementia in a Hearing-impaired Population According to Hearing Aid Use: A Nationwide Population-based Study in Korea

Hearing loss is considered a potentially modifiable risk factor for dementia. However, the effect of use of a hearing aid on the development of dementia has not been clearly established. We aimed to assess the incidence of dementia in hearing-impaired individuals according to hearing aid use in a nationwide population-based cohort study with matched controls.This was a retrospective, longitudinal, cohort study of South Korean national claims data for individuals newly registered with hearing disabilities (better ear ≥40 dBHL with worse ear ≥80 dBHL, or better ear ≥60 dBHL) between 2004 and 2008. The hearing aid cohort comprised individuals who received hearing aid subsidies from the National Health Insurance within a year from disability registration. The comparison cohort comprised individuals without a record of a hearing aid claim during the study period after 1:1 matching for audiologic and sociodemographic factors with the hearing aid cohort. The occurrence of dementia was followed up until 2018.Each cohort comprised 8780 individuals. Overall incidence of dementia in the hearing aid and comparison cohorts were 156.0 and 184.5 per 10,000 person-years, respectively (incidence rate ratio = 0.85, 95% confidence interval 0.79-0.91). In a multivariable analysis of the whole study populations, hearing aid use (hazard ratio = 0.75, 95% confidence interval 0.70-0.81) attenuated the risk of dementia.Dementia incidence in individuals with hearing disabilities was lower in hearing aid users than that in nonusers. Hearing rehabilitation with hearing aids should be encouraged for individuals with hearing loss.