Many medical studies record a patient’s race using only the broad categories from the U.S. Census, which may conceal racial health disparities, a new study reports.

Researchers evaluated the performance of clinical risk scores for people of different races in an emergency department (ED). A clinical risk score summarizes the severity of a patient’s symptoms into a single number – the higher the score, the greater the risk of severe health outcomes. The researchers looked at broad race categories, like “Asian,” and more specific subgroups, like “Chinese” and “Indian.” The risk scores performed much better for some subgroups than others, but lumping groups together under broad race categories hid those differences.

“Any time you have a predictive risk score that works better for some groups than for other groups, that’s potentially a problem, because it means that the errors in that risk score may have a bigger impact on some groups than on others,” said senior author Emma Pierson, assistant professor of computer science in the Jacobs Technion-Cornell Institute at Cornell Tech, and in the Cornell Ann S. Bowers College of Computing and Information Science.

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