Hospitalization in community-dwelling persons with Alzheimer's disease: frequency and causes.

OBJECTIVES: To examine the rates of and risk factors for acute hospitalization in a prospective cohort of older community-dwelling patients with Alzheimer's disease (AD). DESIGN: Longitudinal patient registry. SETTING: AD research center. PARTICIPANTS: Eight hundred twenty-seven older persons with AD. MEASUREMENTS: Acute hospitalization after AD research center visit was determined from a Medicare database. Risk factor variables included demographics, dementia-related, comorbidity and diagnoses and were measured in interviews and according to Medicare data. RESULTS: Of the 827 eligible patients seen at the ADRC during 1991 to 2006 (median follow-up 3.0 years), 542 (66%) were hospitalized at least once, and 389 (47%) were hospitalized two or more times, with a median of 3 days spent in the hospital per person-year. Leading reasons for admission were syncope or falls (26%), ischemic heart disease (17%), gastrointestinal disease (9%), pneumonia (6%), and delirium (5%). Five significant independent risk factors for hospitalization were higher comorbidity (hazard ratio (HR)=1.87, 95% confidence interval (CI)=1.57-2.23), previous acute hospitalization (HR=1.65, 95% CI=1.37-1.99), older age (HR=1.51, 95% CI=1.26-1.81), male sex (HR=1.27, 95% CI=1.04-1.54), and shorter duration of dementia symptoms (HR=1.26, 95% CI=1.02-1.56). Cumulative risk of hospitalization increased with number of risk factors present at baseline: 38% with zero factors, 57% with one factor, 70% with two or three factors, and 85% with four or five factors (P(trend) <.001). CONCLUSION: In a community-dwelling population with generally mild AD, hospitalization is frequent, occurring in two-thirds of participants over a median follow-up time of 3 years. With these results, clinicians may be able to identify dementia patients at high risk for hospitalization.