Using Medicare Enrollment Data to Identify Beneficiaries in Assisted Living

Develop an approach for identifying Medicare beneficiaries residing in US assisted living (AL) communities in calendar year 2018.

We used the following data sources: national directory of licensed ALs, file of US addresses and their associated 9-digit ZIP codes (ZIP+4), Medicare Enrollment Database (EDB), Master Beneficiary Summary File (MBSF), and the Minimum Data Set (MDS).

A total of 412,723 Medicare beneficiaries who lived in ZIP+4 codes associated with an AL were identified as residents. Approximately 28% of the 16,682 ALs in which these beneficiaries resided were smaller communities (<25 beds).

For each AL, we identified ZIP+4 codes associated with its address. Using this ZIP+4 file, we searched through the Medicare EDB to identify beneficiaries who lived in each ZIP+4 code. The MBSF and MDS were used to exclude beneficiaries who died before 2018 and those whose AL and nursing home stays overlapped. We identified 3 cohorts of Medicare beneficiaries: (1) residents of a specific AL (one AL address per ZIP+4), (2) most likely AL residents, and (3) not likely AL residents. Comparisons across these cohorts were used to examine construct validity of our approach. Additional comparisons were made to AL residents based on the National Survey of Long-Term Care Providers (NSLTCP) and to fee-for-service (FFS) Medicare community-dwelling and long-stay nursing home residents.

The cohorts of beneficiaries identified as AL residents exhibited good construct validity. AL residents also showed similarity in demographic characteristics to the 2018 sample from the NSLTCP, and as expected were different from FFS community and nursing home beneficiaries.

We developed a methodology for identifying Medicare beneficiaries who reside in ALs. As this residential setting continues to grow, future studies will need effective approaches for identifying AL residents in order to evaluate the quality of care they receive.