title: Infection hospitalization increases risk of dementia in the elderly.
abstract: OBJECTIVE
  Severe infections, often requiring ICU admission, have been associated with persistent cognitive dysfunction. Less severe infections are more common and whether they are associated with an increased risk of dementia is unclear. We determined the association of pneumonia hospitalization with risk of dementia in well-functioning older adults.
  
  
  METHODS
  Secondary analysis of a randomized multicenter trial to determine the effect of Gingko biloba on incident dementia.
  
  
  METHODS
  Five academic medical centers in the United States.
  
  
  METHODS
  Healthy community volunteers (n = 3,069) with a median follow-up of 6.1 years.
  
  
  METHODS
  None.
  
  
  RESULTS
  We identified pneumonia hospitalizations using International Classification of Diseases, 9th Edition-Coding Manual codes and validated them in a subset. Less than 3% of pneumonia cases necessitated ICU admission, mechanical ventilation, or vasopressor support. Dementia was adjudicated based on neuropsychological evaluation, neurological examination, and MRI. Two hundred twenty-one participants (7.2%) incurred at least one hospitalization with pneumonia (mean time to pneumonia = 3.5 yr). Of these, dementia was developed in 38 (17%) after pneumonia, with half of these cases occurring 2 years after the pneumonia hospitalization. Hospitalization with pneumonia was associated with increased risk of time to dementia diagnosis (unadjusted hazard ratio = 2.3; CI, 1.6-3.2; p < 0.0001). The association remained significant when adjusted for age, sex, race, study site, education, and baseline mini-mental status examination (hazard ratio = 1.9; CI, 1.4-2.8; p < 0.0001). Results were unchanged when additionally adjusted for smoking, hypertension, diabetes, heart disease, and preinfection functional status. Results were similar using propensity analysis where participants with pneumonia were matched to those without pneumonia based on age, probability of developing pneumonia, and similar trajectories of cognitive and physical function prior to pneumonia (adjusted prevalence rates, 91.7 vs 65 cases per 1,000 person-years; adjusted prevalence rate ratio = 1.6; CI, 1.06-2.7; p = 0.03). Sensitivity analyses showed that the higher risk also occurred among those hospitalized with other infections.
  
  
  CONCLUSIONS
  Hospitalization with pneumonia is associated with increased risk of dementia.
authors.affiliation: 1Department of Acute and Tertiary Care, School of Nursing, University of Pittsburgh, Pittsburgh, PA. 2Department of Neurology, University of Pittsburgh, Pittsburgh, PA. 3Department of Biostatistics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA. 4National Center for Complementary and Alternative Medicine (NCCAM), National Institutes of Health, Bethesda, MD. 5The Clinical Research, Investigation, and Systems Modeling of Acute Illness Center, University of Pittsburgh, Pittsburgh, PA. 6Department of Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA. 7Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh Medical Center, Pittsburgh, PA. 8Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA. 9Department of Epidemiology, School of Public Health, University of Washington, Seattle, WA. 10Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC. 11Department of Biostatistics, University of Washington, Seattle, WA. 12School of Medicine, University of Virginia, Charlottesville, VA.
authors.forename: Judith A
authors.initials: JA
authors.lastname: Tate
authors.forename: Beth E
authors.initials: BE
authors.lastname: Snitz
authors.forename: Karina A
authors.initials: KA
authors.lastname: Alvarez
authors.forename: Richard L
authors.initials: RL
authors.lastname: Nahin
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Weissfeld
authors.forename: Oscar
authors.initials: O
authors.lastname: Lopez
authors.forename: Derek C
authors.initials: DC
authors.lastname: Angus
authors.forename: Faraaz
authors.initials: F
authors.lastname: Shah
authors.forename: Diane G
authors.initials: DG
authors.lastname: Ives
authors.forename: Annette L
authors.initials: AL
authors.lastname: Fitzpatrick
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Williamson
authors.forename: Alice M
authors.initials: AM
authors.lastname: Arnold
authors.forename: Steven T
authors.initials: ST
authors.lastname: DeKosky
authors.forename: Sachin
authors.initials: S
authors.lastname: Yende
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003704:Dementia / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D006760:Hospitalization; D006801:Humans; D008297:Male; D011014:Pneumonia / Q000150:complications*; D015995:Prevalence; D057216:Propensity Score; D011569:Psychiatric Status Rating Scales; D012306:Risk; D012307:Risk Factors; D014481:United States / Q000453:epidemiology