Survival after initial diagnosis of Alzheimer disease

Abstract

Background: Alzheimer disease is an increasingly common condition in older people. Knowledge of life expectancy after the diagnosis of Alzheimer disease and of associations of patient characteristics with survival may help planning for future care.

Objective: To investigate the course of Alzheimer disease after initial diagnosis and examine associations hypothesized to correlate with survival among community-dwelling patients with Alzheimer disease.

Design: Prospective observational study.

Setting: An Alzheimer disease patient registry from a base population of 23 000 persons age 60 years and older in the Group Health Cooperative, Seattle, Washington.

Patients: 521 newly recognized persons with Alzheimer disease enrolled from 1987 to 1996 in an Alzheimer disease patient registry.

Measurements: Baseline measurements included patient demographic features, Mini-Mental State Examination score, Blessed Dementia Rating Scale score, duration since reported onset of symptoms, associated symptoms, comorbid conditions, and selected signs. Survival was the outcome of interest.

Results: The median survival from initial diagnosis was 4.2 years for men and 5.7 years for women with Alzheimer disease. Men had poorer survival across all age groups compared with females. Survival was decreased in all age groups compared with the life expectancy of the U.S. population. Predictors of mortality based on proportional hazards models included a baseline Mini-Mental State Examination score of 17 or less, baseline Blessed Dementia Rating Scale score of 5.0 or greater, presence of frontal lobe release signs, presence of extrapyramidal signs, gait disturbance, history of falls, congestive heart failure, ischemic heart disease, and diabetes at baseline.

Limitations: The base population, although typical of the surrounding Seattle community, may not be representative of other, more diverse populations.

Conclusions: In this sample of community-dwelling elderly persons who received a diagnosis of Alzheimer disease, survival duration was shorter than predicted on the basis of U.S. population data, especially for persons with onset at relatively younger ages. Features significantly associated with reduced survival at diagnosis were increased severity of cognitive impairment, decreased functional level, history of falls, physical examination findings of frontal release signs, and abnormal gait. The variables most strongly associated with survival were measures of disease severity at the time of diagnosis. These results should be useful to patients and families experiencing Alzheimer disease, other caregivers, clinicians, and policymakers when planning for future care needs.