Severe hearing impairment and risk of depression: A national cohort study

OBJECTIVE Hearing impairment is suggested to be associated with depression in the elderly. The present study evaluated the risk of depression after hearing impairment in all age groups matched by age, sex, income, and region of residence. METHODS The Korean Health Insurance Review and Assessment Service-National Patient Samples were collected for a period from 2002 to 2013. Hearing impairment was defined as a hearing threshold ≥ 60 dB in both ears or as ≥ 80 dB in one ear and ≥ 40 dB in one ear. Hearing-impaired participants performed a pure tone audiometry test 3 times and an auditory brainstem response threshold test once. The 6,136 hearing-impaired participants were matched 1:4 with 24,544 controls with no reported hearing impairment for age, sex, income, and region of residence. Depression was investigated based on the International Classification of Disease-10 codes F31 (bipolar affective disorder) through F39 (unspecified mood disorder) by a psychiatrist from 2002 through 2013. The crude (simple) and adjusted (age, sex, income, region of residence, dementia, hypertension, diabetes, and dyslipidemia) hazard ratio (HR) of hearing impairment on depression were analyzed using Cox-proportional hazard model. RESULTS The rate of depression was significantly higher in the severe hearing-impaired group than in the control group (7.9% vs. 5.7%, P < 0.001). Severe hearing impairment increased the risk of depression (adjusted HR = 1.37, 95% confidence interval [CI] = 1.24-1.52, P < 0.001). In a subgroup analysis, young (0-29 years old), middle-aged (30-59 years old), and old (≥ 60 years old) severe hearing-impaired groups showed significantly increased risk of depression compared to controls with no reported hearing impairment. In accordance with income level, severe hearing impairment elevated depression in the low and high income groups, but not in the middle income group. CONCLUSION Severe hearing impairment increased the risk of depression independently of age, sex, region, past medical histories, and income (in low and high income persons but not in middle income persons).