SEER-Medicare: Medicare Enrollment, Claims, and Assessment Data

Medicare is the federally funded program that provides health insurance for the elderly, persons with end-stage renal disease, and some individuals with disabilities. For persons age 65 and over, 97 percent are eligible for Medicare. Almost all Medicare beneficiaries have Part A coverage that includes hospital, skilled-nursing facility, hospice and some home health care. 96 percent of elderly Part A beneficiaries choose to pay a monthly premium to enroll in Part B of Medicare that covers physician and outpatient services. Medicare Part C refers to Medicare Advantage (MA) enrollment (e.g., enrollment in Managed Care or an HMO). While Historically most Medicare beneficiaries were enrolled in fee-for-service (FFS) coverage, enrollment in MA has steadily increased; in 2023, more than half of Medicare beneficiaries were enrolled in MA. In 2006, Medicare initiated Part D, which provides prescription drug coverage for beneficiaries who purchase the benefit. In 2008, the Centers for Medicare & Medicaid Services (CMS) estimated that approximately 60% of beneficiaries have Part D coverage; the percentage has increased over the past decade to approximately 70%. Prior to 2015, only Medicare claims (e.g., inpatient, outpatient bills) were available, allowing assessments of utilization and outcomes only among persons with FFS coverage. However, now that Medicare encounter data are available similar assessments can now be made among persons enrolled in MA,

Information about Medicare eligibility and enrollment is available for all persons included in the SEER-Medicare data (both persons with and without a cancer diagnosis). Medicare claims (e.g., inpatient, outpatient bills) are available only for persons with FFS coverage. Part D prescription encounter data is available for persons with HMO and FFS coverage. Healthcare assessments for persons enrolled in nursing homes and home healthcare are also available for persons with HMO and FFS coverage. For more information about Medicare data, please see the Research Data Assistance Center (ResDAC) website and the Chronic Conditions Warehouse (CCW) website.