title: Moderate and severe obesity have large differences in health care costs.
abstract: OBJECTIVE
  To analyze health care use and expenditures associated with varying degrees of obesity for a nationally representative sample of individuals 54 to 69 years old.
  
  
  METHODS
  Data from the Health and Retirement Study, a nationwide biennial longitudinal survey of Americans in their 50s, were used to estimate multivariate regression models of the effect of weight class on health care use and costs. The main outcomes were total health care expenditures, the number of outpatient visits, the probability of any inpatient stay, and the number of inpatient days.
  
  
  RESULTS
  The results indicated that there were large differences in obesity-related health care costs by degree of obesity. Overall, a BMI of 35 to 40 was associated with twice the increase in health care expenditures above normal weight (about a 50% increase) than a BMI of 30 to 35 (about a 25% increase); a BMI of over 40 doubled health care costs (approximately 100% higher costs above those of normal weight). There was a difference by gender in how health care use and costs changed with obesity class. The primary effect of increasing weight class on health care use appeared to be through elevated use of outpatient health care services.
  
  
  CONCLUSIONS
  Obesity imposes an increasing burden on the health care system, and that burden grows disproportionately large for the most obese segment of the U.S. population. Because the prevalence of severe obesity is increasing much faster than that of moderate obesity, average estimates of obesity effects obscure real consequences for individuals, physician practices, hospitals, and health plans.
authors.affiliation: RAND Graduate School, 1776 Main Street, Santa Monica, CA 90401, USA. tatiana@rand.org
authors.forename: Tatiana
authors.initials: T
authors.lastname: Andreyeva
authors.forename: Roland
authors.initials: R
authors.lastname: Sturm
authors.forename: Jeanne S
authors.initials: JS
authors.lastname: Ringel
mesh_terms: D000368:Aged; D000553:Ambulatory Care / Q000191:economics / Q000706:statistics & numerical data; D015992:Body Mass Index; D001835:Body Weight; D005260:Female; D017048:Health Care Costs; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000145:classification* / Q000191:economics*; D012727:Sex Characteristics