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Analyzing the relationship between obesity and Medicare spending, this study reveals surprising findings on treatment access and costs.
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How Big a Problem is Obesity for the Medicare Program? AcademyHealth June 10, 2008 Bruce Stuart, Lirong Zhao, Jennifer Lloyd The Peter Lamy Center Drug Therapy and Aging University of Maryland Baltimore
Setup • 25% of Medicare beneficiaries are obese (BMI 30 +) • Obese beneficiaries have higher prevalence of diabetes, hypertension, heart failure, osteoarthritis, and other costly diseases compared to normal weight individuals • They also have significantly more ADL limitations and are far more likely to report being in fair or poor health So…. • It stands to reason that obese beneficiaries will have higher annual Medicare spending compared to normal weight (BMI 18.5 -24.9) individuals, right?
Setup However… • This assumes obese beneficiaries receive similar treatment for obesity-related chronic disease compared to normal weight persons with same diseases • Prior research shows that obese people have less access to health services and may be discriminated against by providers
Study Objectives • Assess relationship between BMI and spending on traditional Medicare services and prescription drugs • Determine whether spending associated with obesity-related chronic conditions varies across BMI classes • Derive policy implications for the Medicare program and Part D
Data and Study Sample Data • Pooled panel of MCBS files, 1997 – 2003 Study Sample • Community-dwelling beneficiaries in the fee-for-service sector, enrolled in Part A and Part B throughout the year, with complete MCBS surveys. • Final study sample: 58,491 person-year observations
Measures Obesity • Body Mass Index (BMI) classes: underweight (<18.5), normal (18.5-24.9), overweight (25.0-29.9), obese class I (30.0-34.9), obese class II (35.0-39.9), obese class III (≥40.0) Dependent Variables • Medicare payments for Part A and B services in constant 2006 dollars • Payments for prescription drugs in constant 2006 dollars
Measures Explanatory Variables • Age, sex, race, marital status, education, income, drug coverage, region, metro status, health status, ADL limitations, died during year, calendar year of observation • Obesity-related chronic conditions: diabetes, hypertension, CAD, hyperlipidemia, health failure, COPD/asthma, osteoarthritis, hypothyroidism, GERD, sleep apnea
Analytic Strategy Descriptive Findings • Chart Medicare and drug spending by BMI class Regression Models • Hierarchical models: (1) BMI dummies (normal weight reference), (2) add demographic and socioeconomic variables, (3) add obesity-related chronic conditions • Pooled cross-sections analysis with person-year as unit of analysis. • Dependent variable modeled as a gamma distribution with log link
Selected Descriptive Results • Obesity among Medicare beneficiaries • 16.9% in 1997 • 24.6% in 2003 • Growth rates varied by class of obesity • Class I: 11.7% (1997) to 16.7% (2003) • Class II: 3.5% (1997) 4.9% (2003) • Class III: 1.8% (1997) to 3.1% (2003)
Annual Prescription Drug Spending by BMI Class (1997 and 2003)
Model 1. Unadjusted Marginal Effects of BMI on Medicare and Drug Spending *p <.01 **p <.001
Model 2. Marginal Effects Conditional on Demographic and Economic Factors *p <.01 **p <.001
Model 3. Marginal Effects Conditional on Demographic, Economic, and Morbidity Factors *p <.01 **p <.001
Conclusions • No evidence obese beneficiaries more costly to Medicare over the period 1997 through 2003 (actually somewhat less expensive than normal weight beneficiaries in unadjusted comparisons) • Prescription spending significantly higher for obese beneficiaries, particularly among obese class II and III individuals.
Conclusions • Obese beneficiaries receive fewer and/or less costly traditional Medicare services for obesity-related chronic conditions than normal weight beneficiaries • But, obese beneficiaries make somewhat greater use of prescription drugs in treating these conditions
Study Limitations • Height and weight are self-reported • Drug use is self-reported. • Study prior to advent of Medicare Part D. • 70% had drug coverage (1997-2003) • 90% have drug coverage today
Implications for Medicare • Obesity is a big problem for the Medicare program, but not for the reasons most commonly believed • Rising obesity is unlikely to be a drain on the Medicare Part A and B trust funds • Part D costs will rise as the prevalence of obesity in the Medicare population grows • Conclusion that obese beneficiaries are undertreated for common chronic conditions deserves careful scrutiny