Alzheimer disease and mortality - A 15-year epidemiological study

Background: Alzheimer disease (AD) is considered a leading cause of death, but few studies have examined the contribution of AD to mortality based on follow-up of representative US cohorts. Objective: To examine mortality rates, duration of survival, causes of death, and the contribution of AD to the risk of mortality in an aging community-based cohort, controlling for other predictors. Design: Fifteen-year prospective epidemiological study. Mortality rates per 1000 person-years and the population-attributable risk of mortality were determined. Cox proportional hazards models were used to estimate relative risk of mortality due to AD, adjusting for relevant covariates. Death certificates were abstracted for listed causes of death. Setting: A largely blue-collar rural community in southwestern Pennsylvania. Participants: A community-based cohort of 1670 adults 65 years and older at study enrollment. Main Outcome Measure: Mortality. Results: In the overall cohort, AD was a significant predictor of mortality, with a hazard ratio of 1.4 after adjusting for covariates. The population-attributable risk of mortality from AD was 4.9% based on the same model. Examining the sexes separately, AD increased mortality risk only among women. Death certificates of AD subjects were more likely to list dementia/AD, other brain disorders, pneumonia, and dehydration, and less likely to include cancer. Conclusions: Alzheimer disease was responsible for 4.9% of the deaths in this elderly cohort. Alzheimer disease increased the risk of mortality 40% in the cohort as a whole and separately in women but not in men. The mean (SD) duration of survival with AD was 5.9 (3.7) years, and longer with earlier age at onset.