How SEER, MHOS, and Medicare Data Are Linked

The linkage of the SEER-MHOS data is a collaborative effort of the NCI, the SEER registries, and the Centers for Medicare & Medicaid Services (CMS). NCI and CMS establish the linkages between the three data sources (SEER clinical data, Medicare Part D claims, and MHOS survey data); it is not the responsibility of investigators seeking to use the data. The linkage process is described below:

• To link SEER with Medicare data, the registries participating in the SEER program send individual identifiers for all persons in their files. These identifiers are matched with identifiers contained in Medicare's master enrollment file.
• MHOS survey data are then matched to beneficiaries in the SEER registry using the same identifiers. MHOS data from beneficiaries who did not have cancer according to SEER data but resided in a SEER region for at least 1 day, either in the year that they completed the MHOS survey or in the year prior, were also linked to Medicare Part D claims from CMS.
• A small number of beneficiaries completed more than one MHOS survey, resulting in a slightly greater number of surveys than individual beneficiaries. The linkage of MHOS data to the SEER-Medicare database was first completed in 2011 and updated in 2023. NCI and CMS plan to update the linkage every 2-3 years based on SEER and other data availability.