title: Depression and risk of hospitalization for pneumonia in a cohort study of older Americans.
abstract: OBJECTIVE
  The aim of this study is to determine if depression is independently associated with risk of hospitalization for pneumonia after adjusting for demographics, medical comorbidity, health-risk behaviors, baseline cognition and functional impairments.
  
  
  METHODS
  This secondary analysis of prospectively collected data examined a population-based sample of 6704 Health and Retirement Study (HRS) (1998-2008) participants>50years old who consented to have their interviews linked to their Medicare claims and were without a dementia diagnosis. The eight-item Center for Epidemiologic Studies Depression Scale and/or International Classification of Disease, Ninth Revision, Clinical Modification (ICD-9-CM) depression diagnoses were used to identify baseline depression. ICD-9-CM diagnoses were used to identify hospitalizations for which the principal discharge diagnosis was for bacterial or viral pneumonia. The odds of hospitalization for pneumonia for participants with depression relative to those without depression were estimated using logistic regression models. Population attributable fractions were calculated to determine the extent that hospitalizations for pneumonia could be attributable to depression.
  
  
  RESULTS
  After adjusting for demographic characteristics, clinical factors, and health-risk behaviors, depression was independently associated with increased odds of hospitalization for pneumonia (odds ratio [OR]: 1.28, 95% confidence interval [95%CI]: 1.08, 1.53). This association persisted after adjusting for baseline cognition and functional impairments (OR: 1.24, 95%CI: 1.03, 1.50). In this cohort, 6% (95%CI: 2%, 10%) of hospitalizations for pneumonia were potentially attributable to depression.
  
  
  CONCLUSIONS
  Depression is independently associated with increased odds of hospitalization for pneumonia. This study provides additional rationale for integrating mental health care into medical settings in order to improve outcomes for older adults.
authors.affiliation: Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA, USA. Electronic address: ddavydo1@u.washington.edu.
authors.forename: Dimitry S
authors.initials: DS
authors.lastname: Davydow
authors.affiliation: Department Internal Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Catherine L
authors.initials: CL
authors.lastname: Hough
authors.affiliation: Ann Arbor Veterans Affairs Center for Clinical Management Research, Ann Arbor, MI, USA; Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA; Institute for Social Research, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Kara
authors.initials: K
authors.lastname: Zivin
authors.affiliation: Ann Arbor Veterans Affairs Center for Clinical Management Research, Ann Arbor, MI, USA; Institute for Social Research, University of Michigan, Ann Arbor, MI, USA; Department of Medicine, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Langa
authors.affiliation: Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA, USA.
authors.forename: Wayne J
authors.initials: WJ
authors.lastname: Katon
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D015897:Comorbidity; D003863:Depression / Q000453:epidemiology*; D003866:Depressive Disorder / Q000453:epidemiology*; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011014:Pneumonia; D018570:Risk Assessment; D012307:Risk Factors; D014481:United States / Q000453:epidemiology
keywords: Depression; Hospitalization; Outcome assessment (health care); Pneumonia