Interpreting p-tau217 on the ward: frailty and plasma biomarkers in acutely admitted older adults.

INTRODUCTION: Older adults living with frailty are prone to adverse events upon acute hospitalization. Frailty biomarkers aiding early identification are lacking. This study explores frailty and Alzheimer's disease (AD)-related biomarkers. METHODS: Participants were recruited from the Norfrail study (n = 178) and from the Norwegian Dementia Disease Initiative (n = 105). Linear regression was used to analyze associations between frailty and the plasma biomarkers phosphorylated tau-217 (p-tau217), neurofilament light chain (NfL), brain-derived tau, ubiquitin carboxyl-terminal hydrolase L1, and glial fibrillary acidic protein in older adults admitted acutely to hospital. RESULTS: No significant association was found between p-tau217 and frailty. Estimated glomerular filtration rate (eGFR) explained 27% of the variance of plasma p-tau217 (p < 0.001). NfL was the only biomarker significantly associated with frailty (p < 0.01). DISCUSSION: Except for NfL, plasma biomarkers were independent of frailty. Substantial p-tau217 variability was explained by eGFR. Clinicians need to consider renal function when interpreting p-tau217 in unselected populations.