Introduction
Phosphorylated tau (p‐tau)181 has become a promising blood‐based Alzheimer's disease (AD) biomarker. We studied the agreement of plasma p‐tau181 and cerebrospinal fluid (CSF) markers in patients with alteration of consciousness (AOC).
Methods
Plasma and CSF were simultaneously collected in participants presenting with AOC. Plasma p‐tau181 was measured using the single‐molecule array. CSF biomarkers were classified according to the amyloid/tau/neurodegeneration (AT[N]) framework.
Results
Among participants enrolled, the median (interquartile range) age was 57 (28.5–75) years and 5.8% had AD. Plasma p‐tau181 yielded area under the curve of 0.85 and showed moderate correlation with CSF p‐tau181 (Rho = 0.42,
P
< .001). Using the historical cut‐point, many non‐AD participants had elevated plasma p‐tau181 resulting in a specificity of 0.57. Plasma p‐tau181 correlated with the glomerular filtration rate (Rho = –0.52,
P
< .001). Among A− participants with elevated plasma p‐tau181, 42% had kidney dysfunction.
Discussion
Plasma p‐tau181 showed inadequate specificity in patients with AOC partially attributable to concomitant kidney dysfunction.
Introduction: Despite the substantial accuracy of plasma p-tau in diagnosing Alzheimer's disease (AD) in research cohorts, data on real-life memory clinic patients are lacking.
Methods:Memory clinic patients at their early symptomatic stages were prospectively enrolled to undergo routine clinical assessment, plasma p-tau181 quantification (Simoa), amyloid and tau-positron emission tomography (PET). The diagnostic performance of plasma p-tau181, neurocognitive specialists, and regional tau-PET were compared head-to-head using amyloid-PET as the reference standard.Results: Plasma p-tau181 has the area under the curve (AUC), sensitivity, specificity, and accuracy of 0.84 (95% confidence interval [CI] 0.73-0.94), 0.80 (95% CI 0.64-0.90), 0.75 (95% CI 0.51-0.90), and 0.78 (95% CI 0.65-0.88) for detecting amyloid-PET positivity in early symptomatic patients, respectively. The AUC of clinical diagnosis and tau-PET were 0.70 (95% CI 0.56-0.85) and 0.88 (95% CI 0.79-0.97), respectively. Discussion: Plasma p-tau181 also performed well in real-life memory clinic settings and its role in clinical practice is supported.
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