title: Association of incident dementia with hospitalizations.
abstract: BACKGROUND
  Dementia is associated with increased rates and often poorer outcomes of hospitalization, including worsening cognitive status. New evidence is needed to determine whether some admissions of persons with dementia might be potentially preventable.
  
  
  OBJECTIVE
  To determine whether dementia onset is associated with higher rates of or different reasons for hospitalization, particularly for ambulatory care-sensitive conditions (ACSCs), for which proactive outpatient care might prevent the need for a hospital stay.
  
  
  METHODS
  Retrospective analysis of hospitalizations among 3019 participants in Adult Changes in Thought (ACT), a longitudinal cohort study of adults aged 65 years or older enrolled in an integrated health care system. All participants had no dementia at baseline and those who had a dementia diagnosis during biennial screening contributed nondementia hospitalizations until diagnosis. Automated data were used to identify all hospitalizations of all participants from time of enrollment in ACT until death, disenrollment from the health plan, or end of follow-up, whichever came first. The study period spanned February 1, 1994, to December 31, 2007.
  
  
  METHODS
  Hospital admission rates for patients with and without dementia, for all causes, by type of admission, and for ACSCs.
  
  
  RESULTS
  Four hundred ninety-four individuals eventually developed dementia and 427 (86%) of these persons were admitted at least once; 2525 remained free of dementia and 1478 (59%) of those were admitted at least once. The unadjusted all-cause admission rate in the dementia group was 419 admissions per 1000 person-years vs 200 admissions per 1000 person-years in the dementia-free group. After adjustment for age, sex, and other potential confounders, the ratio of admission rates for all-cause admissions was 1.41 (95% confidence interval [CI], 1.23-1.61; P < .001), while for ACSCs, the adjusted ratio of admission rates was 1.78 (95% CI, 1.38-2.31; P < .001). Adjusted admission rates classified by body system were significantly higher in the dementia group for most categories. Adjusted admission rates for all types of ACSCs, including bacterial pneumonia, congestive heart failure, dehydration, duodenal ulcer, and urinary tract infection, were significantly higher among those with dementia.
  
  
  CONCLUSIONS
  Among our cohort aged 65 years or older, incident dementia was significantly associated with increased risk of hospitalization, including hospitalization for ACSCs.
authors.affiliation: Division of Gerontology and Geriatric Medicine, Department of Medicine, School of Public Health and Community Medicine, University of Washington, Seattle, WA 98104-2499, USA. phelane@uw.edu
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Phelan
authors.forename: Soo
authors.initials: S
authors.lastname: Borson
authors.forename: Louis
authors.initials: L
authors.lastname: Grothaus
authors.forename: Steven
authors.initials: S
authors.lastname: Balch
authors.forename: Eric B
authors.initials: EB
authors.lastname: Larson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000553:Ambulatory Care; D002908:Chronic Disease / Q000453:epidemiology / Q000628:therapy; D015331:Cohort Studies; D003704:Dementia / Q000453:epidemiology*; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D012306:Risk