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.
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.
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.