Health Characteristics of Medicare traditional fee-for-service and Medicare Advantage enrollees: 1999-2004 NHANES linked to 2007 Medicare data
Lisa Mirel, National Center for Health Statistics 
*Jennifer D. Parker, National Center for Health Statistics 
Gloria Wheatcroft, National Center for Health Statistics 

Keywords: National Health and Nutrition Examination Survey, Medicare, Managed care, Medicare advantage plan, Centers for Medicare and Medicaid Services

A handful of studies have indicated that Medicare beneficiaries who opt into managed care plans are healthier than those who do not. To date, physical examination data have not been used to compare the health status of enrollees in Medicare Advantage plans and traditional fee-for-service (FFS) plans. Recently the 1999-2004 National Health and Nutrition Examination Survey (NHANES), a nationally representative survey of the non-institutionalized population, was linked to Centers for Medicare and Medicaid Services (CMS) beneficiary data from 1999-2007. Using demographic and examination data collected in NHANES, we compared baseline characteristics for beneficiaries 65 years or older in FFS and Medicare Advantage plans in 2007. All analyses accounted for the complex sample design of the survey and used sample examination weights from NHANES that accounted for the unequal probabilities of selection and non-response. The sample examination weights were further adjusted for respondents who could not be linked or did not have data on the 2007 Medicare Denominator file. In 2007, an estimated 25% of these Medicare beneficiaries were enrolled in Medicare Advantage. More non-Hispanic black (33%) and Mexican American beneficiaries (34%) were enrolled in Medicare Advantage than non-Hispanic white beneficiaries (23%). However, there was no evidence of “selection bias” by gender, education, or health characteristics into Medicare Advantage. Relationships between enrollment and hypertension, diabetes, , and high total cholesterol were not significantly different overall or by race/ethnicity. For example, high blood pressure among non-Hispanic white beneficiaries was similar for those in Medicare Advantage and FFS plans (62% vs. 66% respectively). Further analysis of linked data files will increase our understanding of selection into Medicare plans; however, analyses of these files are complicated by analytic sample construction, multiple survey years, multiple enrollment years, benefit eligibility, and survey design and statistical power constraints that limit geographic assessment.