Contribution of Alzheimer disease to mortality in the United States

Abstract

Objective: To assess the burden of mortality attributable to Alzheimer disease (AD) dementia in the United States.

Methods: Data came from 2,566 persons aged 65 years and older (mean 78.1 years) without dementia at baseline from 2 cohort studies of aging with identical annual diagnostic assessments of dementia. Because both studies require organ donation, ascertainment of mortality was complete and dates of death accurate. Mortality hazard ratios (HRs) after incident AD dementia were estimated per 10-year age strata from proportional hazards models. Population attributable risk percentage was derived to estimate excess mortality after a diagnosis of AD dementia. The number of excess deaths attributable to AD dementia in the United States was then estimated.

Results: Over an average of 8 years, 559 participants (21.8%) without dementia at baseline developed AD dementia and 1,090 (42.4%) died. Median time from AD dementia diagnosis to death was 3.8 years. The mortality HR for AD dementia was 4.30 (confidence interval = 3.33, 5.58) for ages 75-84 years and 2.77 (confidence interval = 2.37, 3.23) for ages 85 years and older (too few deaths after AD dementia in ages 65-74 were available to estimate HR). Population attributable risk percentage was 37.0% for ages 75-84 and 35.8% for ages 85 and older. An estimated 503,400 deaths in Americans aged 75 years and older were attributable to AD dementia in 2010.

Conclusions: A larger number of deaths are attributable to AD dementia in the United States each year than the number (<84,000 in 2010) reported on death certificates.

Figure. Predicted survival past age 75 years after a diagnosis of AD dementia vs no diagnosis of AD dementia

Estimates for white females with 15 years of education, Alzheimer disease (AD) diagnosed at age 75 years. Red = predicted survival after a diagnosis of AD; blue = predicted survival without AD.