I. Finding and Using Healthcare Data

4. How do I obtain Medi-Cal or Medicare data?

The Centers for Medicare & Medicaid Services (CMS) is responsible for administering Medicare. It also works in with states to administer Medicaid (in California Medicaid is referred to as Medi-Cal).

As the administering agency, HCFA makes some utilization datasets available for researchers. These datasets come in two flavors-Public Use Files (PUFs) and Beneficiary Encrypted Files (BEFs). As it suggests, the PUFs are at an aggregated level and have no information that can be used to link files to patients. On the other hand, BEFs provide encounter level data, but the social security number is scrambled. If you need to identify the Medicare beneficiaries, then the researcher must obtain special permission to access the research identifiable files (RIFs). Obtaining a RIF is very complicated and HCFA will only release RIFs to certain researchers for specific projects; obtaining a BEF is more complicated than getting a PUF.

The PUFs are free (see the CMS web site), RIFs and BEFs cost money and require human subjects approval to use the data.

There are many inpatient and outpatient files available for Medicare and Medicaid. For more information, contact the Research Data Assistance Center (ResDAC). They have a HCFA contract to provide technical assistance. They can answer questions about access to data. They also provide limited technical assistance to help researchers identify questions that can be answered with the data.