The expanded racial and ethnic codes in the Medicare data files: their completeness of coverage and accuracy.

OBJECTIVES: This paper evaluates the new race/ethnicity codes for Asian Americans, Hispanics, and Native Americans that have recently been added to the Medicare enrollment database.
METHODS: The race/ethnicity code revisions made by the Health Care Financing Administration are described and evaluated by (1) comparing the numbers of persons identified as Asian Americans, Hispanics, and Native Americans with corresponding population census projections and (2) determining whether Medicare enrollees born in Asian and Hispanic countries are assigned Asian and Hispanic codes.
RESULTS: Among persons 65 years of age and older, approximately 24% of Hispanics, 17% of Native Americans, and 56% of Asian Americans are identifiable by the new codes. From 18% to 29% of enrollees 65 years old or older born in Mexico, Puerto Rico, and Cuba are coded as Hispanic, and from 14% to 73% of enrollees born in nine Asian countries are classified as Asian American. Classification is not random but is related to timing of migration and to country of origin.
CONCLUSIONS: Researchers should resist the temptation to base analyses on the revised Health Care Financing Administration race/ethnicity codes, since coverage is incomplete and biased.