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Medicare Administrative Data


CMS collects and synthesizes Medicare enrollment, spending, and claims data to monitor and evaluate access to and quality of care, trends in utilization, changes in payment policy, and other program-related issues.

Centers for Medicare & Medicaid Services
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: 
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 beneficiaries who filed claims.

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.

Response Rates and Sample Size: 
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.