title: The impact of influenza vaccination on hospitalizations and mortality among frail older people.
abstract: OBJECTIVE
  The objective of this study was to evaluate the benefits of influenza vaccination against hospitalization and mortality on frail elderly people.
  
  
  METHODS
  The design was a population-based retrospective cohort study.
  
  
  METHODS
  Taiwan's National Health Insurance claims data.
  
  
  METHODS
  Participants were 5063 frail seniors, followed up for four years.
  
  
  METHODS
  Measurements included age, gender, socioeconomic status, living areas, use of annual health examinations, comorbid conditions, use of influenza vaccine, frailty as defined by the Adjusted Clinical Group, hospitalization, and mortality in the observation period. The efficacy was presented as comparing ever versus never vaccinated people during the entire study period without regard to seasons.
  
  
  RESULTS
  Compared with those without influenza vaccination, vaccinated elderly individuals were younger, more likely to be men, have higher socioeconomic status, live in rural areas, have a higher rate of receiving a health examination, and have similar medical conditions. In the Cox proportional hazards analysis, influenza vaccination reduced by 7% the risk of hospitalization (95% confidence interval [CI] 0.86-0.99) and by 44% the risk of mortality (95% CI 0.51-0.62).
  
  
  CONCLUSIONS
  Influenza vaccination was effective against hospitalization and mortality among the frail elderly. These results uphold the current universal influenza vaccination policy, and encourage policymakers to adopt strategies to improve vaccination use.
authors.affiliation: Institute of Hospital and Health Care Administration, National Yang-Ming University, Taipei, Taiwan; Institute of Public Health, National Yang-Ming University, Taipei, Taiwan; Division of Geriatric Medicine, Taipei Veterans General Hospital, Yuan Shan Branch, I-Lan County, Taiwan.
authors.forename: Wei-Ju
authors.initials: WJ
authors.lastname: Lee
authors.affiliation: Institute of Public Health, National Yang-Ming University, Taipei, Taiwan; Aging and Health Research Center, National Yang-Ming University, Taipei, Taiwan; Center for Geriatrics and Gerontology, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Liang-Kung
authors.initials: LK
authors.lastname: Chen
authors.affiliation: Institute of Hospital and Health Care Administration, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Gau-Jun
authors.initials: GJ
authors.lastname: Tang
authors.affiliation: Institute of Hospital and Health Care Administration, National Yang-Ming University, Taipei, Taiwan; Department of Public Health, China Medical University, Taichung, Taiwan. Electronic address: tylan@ym.edu.tw.
authors.forename: Tzuo-Yun
authors.initials: TY
authors.lastname: Lan
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D016330:Frail Elderly; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D017589:Immunization Programs; D007252:Influenza Vaccines; D007251:Influenza, Human / Q000453:epidemiology / Q000401:mortality / Q000517:prevention & control*; D007345:Insurance Claim Review; D008297:Male; D012189:Retrospective Studies; D013624:Taiwan / Q000453:epidemiology
chemical_list: D007252:Influenza Vaccines
keywords: Influenza vaccination; death; hospitalization; older adults