The mediating effect of depression on the association of hearing loss with all-cause and cardiovascular mortality: a prospective cohort study

Depression has been hypothesized to act as a mediator linking hearing loss to mortality; however, existing evidence remains limited and inconsistent. We aimed to investigate the potential mediating role of depression on the association of hearing loss with all-cause and cardiovascular mortality using a large, nationally representative prospective cohort of the U.S. population. This cohort study included 9,827 adults from the 2005–2018 National Health and Nutrition Examination Survey (NHANES). Multivariable Cox proportional hazards models were applied to examine the relationships of hearing loss and depression with all-cause and cardiovascular mortality. Multivariable linear regression was conducted to assess the link between hearing loss and depression. Mediation analysis was conducted to explore the mediating role of depression in the link between hearing loss and mortality outcomes. After adjusting for confounders, both hearing loss and depression showed positive associations with all-cause and cardiovascular mortality, as well as with each other. Mediation analyses revealed that depression mediated the associations between speech-frequency, low-frequency, and high-frequency hearing loss and all-cause mortality by 10.28%, 10.15%, and 9.27%, respectively. For cardiovascular mortality, depression accounted for 11.40%, 11.25%, and 11.67% of the associations, respectively. Significant and stable mediation effects were also observed across various hearing frequency ranges (0.5–8 kHz). These findings underscore the substantial impact of depression on all-cause and cardiovascular mortality risks in individuals with hearing loss. Integrating routine depression screening and targeted mental health interventions into hearing loss management strategies is crucial to mitigating mortality outcomes in this population.