P‐tau217 testing impact on intended management of patients presenting with cognitive impairment: A randomized clinical utility study

INTRODUCTION Plasma biomarkers are minimally invasive tool for identifying Alzheimer's disease pathology. However, evaluation of their clinical utility remains limited. METHODS This ongoing, open‐label, randomized, two‐arm, multicenter, U.S., prospective, observational study enrolled 609 patients presenting for initial evaluation of cognitive impairment. Patients were randomized into tau phosphorylated at position 217 (p‐tau217) tested ( n = 391) and untested ( n = 218) arms. RESULTS Change in working diagnosis was observed for 70.5% of patients with a t‐tau217 result (positive or negative) inconsistent with baseline working diagnosis compared to 2.3% with a result consistent with baseline working diagnosis and 15.6% of untested patients. When the result was consistent with baseline working diagnosis, a significant 15.7% increase in diagnostic confidence was observed compared to 1.7% in untested patients and 5.0% when the result was inconsistent with baseline working diagnosis. DISCUSSION P‐tau217 testing changed health care providers’ intended management and working diagnosis and increased confidence in the diagnosis. Highlights Evaluation of the clinical utility of plasma tau phosphorylated at position 217 (p‐tau217) for identifying Alzheimer's disease pathology has been limited. In this study, the impact of p‐tau testing on health care providers’ diagnostic thinking in patients under evaluation for cognitive impairment was assessed. When the result was inconsistent with the working diagnosis, a change in the working diagnosis was observed in 70.5% of tested patients. When the result was consistent, diagnostic confidence increased by 15.7%. P‐tau217 testing demonstrated clinical utility by changing the working diagnosis, increasing diagnostic confidence, and altering intended patient management.