Downstream of hearing loss: a population-based multistate analysis of lifetime risk and years lived with hearing loss, dementia and their comorbidity in Finland.

backgroundHearing loss (HL) is a major modifiable risk factor of dementia, yet gaps persist regarding its association with years lived with dementia, lifetime risk differences by HL status, and sociodemographic disparities.

methodsUsing Finnish register data on all residents aged 60-99 from 2009-2019 (N=1,987,876; 16,439,107 person-years) and discrete-time multistate modeling, we calculated age-specific transition probabilities between five states - healthy, HL, dementia, comorbidity (both HL and dementia), and death, stratified by sex and education. We then estimated state-specific expectancies and lifetime risk.

resultsAt age 60, males and females in the overall population were expected to live 3.39 and 3.61 years with HL, and 1.09 and 1.85 years with dementia, respectively. Lifetime risk of HL was 22.7% for both sexes; dementia risk was 21.4% for males and 31.0% for females. When examining subpopulations defined by origin state at age 60, those who were healthy could expect 1.10 (males) and 1.89 (females) years with dementia. Meanwhile, those with HL at age 60: 1.90 years (males) and 2.82 years (females) with both HL and dementia (comorbidity). Their lifetime risk of comorbidity was 33.5% (males) and 42.9% (females) - about 1.5 times higher than the dementia risk for those starting healthy. Higher education was associated with longer life, more years across all states, and higher lifetime risks.

conclusionsThese findings illustrate how HL at age 60 is associated with a redistribution of remaining years toward dementia, providing new insight into the joint burden of sensory and cognitive aging.