title: Long-term obesity and avoidable hospitalization among younger, middle-aged, and older adults.
abstract: BACKGROUND
  Avoidable hospitalizations are considered to result from conditions that are preventable with timely and effective ambulatory care. We examined whether obesity, particularly long-term obesity, is associated with risk for and frequency of avoidable hospital stays.
  
  
  METHODS
  Data were drawn from the First National Health and Nutrition Examination Survey Epidemiological Follow-up Survey, a 20-year study of adults aged 25 to 74 years (N = 6833). Using measures of body mass index (BMI) (calculated as weight in kilograms divided by height in meters squared) at baseline and at 25 years of age, we estimated the effect of obesity (BMI > or =30.0) on avoidable hospitalization risk using Cox proportional hazards models, and we estimated its influence on the rate of avoidable stays per year using interval regression models. All multivariate analyses were adjusted for morbidity and other covariates.
  
  
  RESULTS
  One thousand twenty-three subjects experienced a hospitalization considered avoidable. Compared with normal-weight subjects, the adjusted hazard ratio of an avoidable stay among obese subjects was 1.82 (95% confidence interval [CI], 1.31-2.51) for those aged 25 to 44 years, 1.29 (95% CI, 1.05-1.59) for those aged 45 to 64 years, and 1.46 (95% CI, 1.23-1.74) for those 65 years and older. Among participants aged 45 to 64 years at baseline, obesity at 25 years of age was strongly associated with both the risk (hazard ratio, 1.91; 95% CI, 1.59-2.29) and frequency (beta coefficient, 0.057; SE, 0.018) of avoidable stays when accounting for baseline BMI category and additional covariates. For subjects 65 years and older, obesity at 25 years of age was associated with increased risk of avoidable hospitalization (hazard ratio, 1.87; 95% CI, 1.14-3.08) and with increased frequency of such admissions (beta coefficient, 0.138; SE, 0.038).
  
  
  CONCLUSIONS
  As indicated by its association with avoidable hospitalizations, long-term obesity is a substantial risk for complications in medical care. Interventions should target obesity early in the life course to help improve lifelong delivery of ambulatory care and to reduce strains on health care resources.
authors.affiliation: Center on Aging and the Life Course, Purdue University, 302 Wood Street, West Lafayette, IN 47907-2018, USA. mhschafe@purdue.edu
authors.forename: Markus H
authors.initials: MH
authors.lastname: Schafer
authors.forename: Kenneth F
authors.initials: KF
authors.lastname: Ferraro
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D015992:Body Mass Index; D002908:Chronic Disease; D015897:Comorbidity; D005260:Female; D005500:Follow-Up Studies; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D009765:Obesity / Q000150:complications / Q000453:epidemiology*; D012307:Risk Factors; D014481:United States / Q000453:epidemiology