Calculating multirace categories and race-specific rates: a cautionary note to rural health researchers and analysts

Revised federal standards for racial and ethnic data have resulted in 57 new self-selected multirace categories that cannot be directly compared with traditional "one-race-only" categories. "Bridge methods" are available, but each produces different estimates of single-race populations, raising concern about the potential influence on calculated rates for rural and nonmetropolitan areas.

to examine the potential impact of several bridge methods when calculating race-specific mortality rates.

Population and mortality data were collected for 75 counties in Arkansas, and race-specific mortality rates were calculated using 3 deterministic bridging methods: (1) Equal Fractions, (2) Largest Group, and (3) Largest Group Other Than White. The mortality rates were compared at the state and metropolitan/nonmetropolitan levels, as well as for 4 rural substate regions.

Variable rates were obtained from different methods. Estimated mortality rates for the largest single-race groups, White and Black, varied only slightly by method at the state and nonmetropolitan/metropolitan levels. The rural substate regions with the smallest Black populations showed the greatest variation between method-estimated rates for Blacks.

The results suggest that the smallest minority race categories are exceedingly susceptible to the impact of bridge method selection, especially in nonmetropolitan substate regions.