The Benefit of the Doubt Phenomenon in Emergency Triage Assignment Disparities.

Emergency department (ED) triage decisions critically impact patient care and are standardized, yet ethnoracial disparities in triage assignment are well documented. We analyzed ethnoracial differences in triage assignments across four U.S. EDs (two adult, two pediatric), comprising 1.4 million encounters from 2011-2025. To better characterize these disparities, we developed an automated triage algorithm that replicates the Emergency Severity Index (ESI) criteria, the standard triage protocol used at each site. The algorithm identifies high-acuity symptoms and danger-zone vital signs that inform triage decisions at the level-2 (emergent) versus level-3 (urgent) boundary. We compared nurse triage assignments across ethnoracial groups, stratified by algorithmic ESI scores, using causal inference methods to adjust for clinical presentation and hospital context. Significant ethnoracial disparities in triage assignment were observed across all sites. Disparities were concentrated among patients algorithmically classified as lower risk but assigned higher acuity by nurses. This pattern is consistent with a "benefit-of-the-doubt" disparity, in which relatively stable, non-Hispanic White patients are more often assigned higher priority than Hispanic and non-Hispanic Black patients with comparable presentations. By contrast, disparities were attenuated or absent among patients deemed high risk by both nurses and the algorithm. Finally, analysis of the projected length-of-stay impact of substituting nurse-assigned with algorithmic triage scores suggests that algorithmic ESI decision support could reduce triage disparities with minimal effects on patient flow.