Plasma p‐tau217 and cognitive impairment: Evaluating biomarker equity across racial/ethnic groups in HABS‐HD

INTRODUCTION: Plasma phosphorylated tau 217 (p-tau217) is a leading blood-based biomarker of Alzheimer's disease. Its performance in underrepresented racial/ethnic groups remains insufficiently characterized. METHODS: We analyzed 2798 participants from the Health and Aging Brain Study-Health Disparities, including non-Hispanic White, non-Hispanic Black, and Hispanic adults. Multivariable logistic regression and receiver operating characteristic analyses assessed associations and discriminative accuracy between plasma p-tau217 and clinical cognitive impairment with racial/ethnic-specific thresholds. RESULTS: Across all groups, p-tau217 levels were higher in cognitively impaired than unimpaired participants. Elevated p-tau217 was associated with greater odds of cognitive impairment in all racial and ethnic groups. Discriminative accuracy was modest but significant (area under the curve 0.65-0.72), with highest performance in non-Hispanic Black and lowest in Hispanic participants. DISCUSSION: Plasma p-tau217 is robustly associated with cognitive impairment across diverse populations with varying thresholds, highlighting the need for population-specific calibration to support equitable biomarker implementation.