Medicare Administrative Data

Years Available
Some data files are available as far back as 1987, but the Centers for Medicare and Medicaid Services (CMS) no longer provides technical support for files with data prior to 1991.
Mode of Collection
Abstraction of administrative/claims data.
Medicare administrative data or Medicare Fee-for-Service claims (administrative) data, also known as health services utilization data, are collected by the Centers for Medicare and Medicaid Services (CMS) and derived from reimbursement information or the payment of bills. Claims data are clinically valid and include various key attributes related to care such as admission and discharge dates, diagnoses and procedure codes, source of care, date of death, and demographic data (e.g., age, race and ethnicity, place of residence). Medicare claims data can be linked to various other data sources from the U.S. Census Bureau, the Veteran's Administration (VA), the National Death Index (NDI), and the Surveillance, Epidemiology, and End Results Program (SEER).
Selected Content
Data include claims information for services furnished to Medicare beneficiaries and Medicare enrollment data. Claims data include type of service, procedures, diagnoses, dates of service, charge amounts, and payment amounts. Enrollment data include date of birth, sex, race or ethnicity, and reason for entitlement.
Population Covered
Enrollment data are for all persons enrolled in the Medicare program. Claims data include data for Medicare fee-for-service beneficiaries who filed claims. Claims data are not included for beneficiaries enrolled in managed care plans.
The claims and utilization data files contain extensive utilization information at various levels of summarization for a variety of providers and services. There are many types and levels of these files: the National Claims History (NCH) files, the Standard Analytic files (SAFs), Medicare Provider and Analysis Review (MEDPAR) files, Medicare enrollment files, and various other files. The Denominator file contains demographic and enrollment data for each beneficiary enrolled in Medicare during a calendar year. This file is used to determine beneficiary demographic characteristics, entitlement, and beneficiary participation in Medicare managed care organizations (MCOs).
Interpretation Issues
Because Medicare managed care programs may not file claims, files based only on claims data will exclude care for persons enrolled in Medicare managed care programs. In addition, to maintain a manageable file size, some files are based on a sample of enrollees, rather than on all Medicare enrollees. Coding changes and the interpretation of Medicare coverage rules have also changed over the life of the Medicare program.