How the SEER, CAHPS, and Medicare Data are Linked

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

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.

CAHPS survey data are then matched to beneficiaries in the SEER registry using the same identifiers. CAHPS 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 CAHPS survey or in the year prior, were also linked to Medicare claims from CMS.

A small number of beneficiaries completed more than one CAHPS survey, resulting in a slightly greater number of surveys than individual beneficiaries. In total, the analytic file contains data from 3,965,949 Medicare beneficiaries, and includes 4,467,618 CAHPS surveys taken between 1997 and 2013. The linkage of CAHPS data to the SEER-Medicare database was first completed in 2011; NCI and CMS plan to update the linkage again in 2017 and every two years thereafter.

The process for matching persons appearing in the SEER data with their Medicare records is described in:

  • Warren JL, Klabunde CN, Schrag D, Bach PB, Riley GF. Overview of the SEER-Medicare data: content, research applications, and generalizability to the United States elderly population. Med Care 2002 Aug;40(8 Suppl):IV-3-18. [View Abstract]External Web Site Policy

The process for linking CAHPS data to SEER and Medicare data is described in greater detail in:

  • Chawla N, Urato M, Ambs A, Schussler N, Hays RD, Clauser SB, Zaslavsky AM, Walsh K, Schwartz M, Halpern M, Gaillot S, Goldstein EH, Arora NK. Unveiling SEER-CAHPS: a new data resource for quality of care research. J Gen Intern Med 2015 May;30(5):641-50. [View Abstract]External Web Site Policy