Plasma phosphorylated tau and cerebrovascular burden predict emergency department use in dependent older patients

Background: Dependent older patients show high risk of adverse health outcomes when admitted to the emergency department (ED). The prompt identification of ED use risk factors in such population is hence needed. While frailty and cognitive impairment are a known clinical risk factors, biomarkers of most prevalent dementias have been scarcely investigated as possible ED use predictors. Within this framework, this prospective study explored whether plasma phospho-tau181 (ptau181) and cerebrovascular burden provide additional predictive value for 6-month ED use in elderly dependent patients, beyond frailty and age. Methods: We collected baseline clinical and laboratory data to validate a 32-item frailty index, while assessing cognitive impairment through the Mini-Mental State Examination. Biomarkers of cognitive impairment included plasma ptau181 and cerebrovascular burden, i.e., the Fazekas Scale. Binomial and Cox regression models tested the biomarkers of cognitive impairment as predictors of ED use, adjusting for frailty and age. The interaction between cognitive impairment biomarkers was explored. Results: Of the 102 recruited patients, 38 visited the ED. In the binomial models, the frailty index (OR = 1.69, p = 0.011) and the Fazekas Scale (OR = 3.57, p = 0.007) predicted ED use. At lower p-tau181 levels, ED admission risk increased only with higher cerebrovascular burden. Conversely, higher p-tau181 levels predicted ED use (OR = 4.90, p = 0.037) irrespective of cerebrovascular burden. No significant predictors of time to ED use emerged. Discussion: Beyond measures of clinical frailty, the routinary employment of cognitive impairment biomarkers may contribute identifying dependent older patients at short-term high risk of ED use, possibly reducing adverse health outcomes in such population.