title: Obesity and medicare expenditure: accounting for age-related height loss.
abstract: To determine the relationship between BMI and Medicare expenditure for adults 65-years and older and determine whether this relationship changes after accounting for misclassification due to age-related height loss. Using a cross sectional study design, the relationship between BMI and fee-for-service Medicare expenditure was examined among beneficiaries who completed the Medicare Current Beneficiary Survey (MCBS) in 2002, were not enrolled in Medicare Health Maintenance Organization, had a self-reported height and weight, and were 65 and older (n = 7,706). Subjects were classified as underweight, normal weight, overweight, obese (obese I), and severely obese (obese II/III). To adjust BMI for the artifactual increase associated with age-related height loss, the reported height was transformed by adding the sex-specific age-associated height loss to the reported height in MCBS. The main outcome variable was total Medicare expenditure. There was a significant U-shaped pattern between unadjusted BMI and Medicare expenditure: underweight $4,581 (P < 0.0003), normal weight $3,744 (P < 0.0000), overweight $3,115 (reference), obese I $3,686 (P < 0.0039), and obese II/III $4,386 (P < 0.0000). This pattern persisted after accounting for height loss: underweight $4,640 (P < 0.0000), normal weight $3,451 (P < 0.0507), overweight $3,165 (reference), obese I $3,915 (P < 0.0010), and obese II/III $4,385 (P < 0.0004) compared to overweight. In older adults, minimal cost is not found at "normal" BMI, but rather in overweight subjects with higher spending in the obese and underweight categories. Adjusting for loss-of-height with aging had little affect on cost estimates.
authors.affiliation: Department of Pharmaceutical Health Services Research, University of Maryland School of Pharmacy, Baltimore, Maryland, USA. nonwu001@umaryland.edu
authors.forename: Nneka C
authors.initials: NC
authors.lastname: Onwudiwe
authors.forename: Bruce
authors.initials: B
authors.lastname: Stuart
authors.forename: Ilene H
authors.initials: IH
authors.lastname: Zuckerman
authors.forename: John D
authors.initials: JD
authors.lastname: Sorkin
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001827:Body Height / Q000502:physiology*; D015992:Body Mass Index; D001837:Body Weights and Measures / Q000379:methods* / Q000592:standards; D003430:Cross-Sectional Studies; D005260:Female; D017048:Health Care Costs / Q000706:statistics & numerical data; D005102:Health Expenditures / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D006278:Medicare / Q000191:economics*; D009765:Obesity / Q000175:diagnosis / Q000191:economics* / Q000453:epidemiology / Q000628:therapy*; D014481:United States