The Master Beneficiary Summary File includes several segments.
Base (A/B/D) segment: This segment includes beneficiary enrollment information, such as the beneficiary unique identifier, state and county codes, zipcode, date of birth, date of death, sex, race, age, monthly entitlement indicators (A/B/D), reasons for entitlement, and monthly managed care indicators (yes/no). As of 2006, it also includes variables specific to enrollment in Part D.
Chronic Conditions segment: This segment includes 27 chronic condition data warehouse flags called CCW Flags. This includes 6 new chronic conditions in addition to the 21 chronic conditions previously defined. For more information about the CCW Flags, please see the CCW User Guide.
Other Chronic or Potentially Disabling Conditions segment: The Other Chronic or Potentially Disabling Conditions segment of the MBSF contains 9 mental health and tobacco use conditions, 15 developmental disorder and disability-related conditions, and 9 other chronic physical and behavioral health conditions which were developed by CMS specifically to enhance research of the Medicare-Medicaid dually enrolled population.
Cost & Utilization segment: This segment includes summarized information about the service utilization and Medicare payment amounts by file type.
National Death Index (NDI) segment: This segment includes the National Death Index cause of death information. This is available for all Medicare beneficiaries from 1999-2008 and for Medicaid recipients from 1999-2007. There are no plans to update the NDI segment.