Aim: Plasma phosphorylated-tau (P-tau) 217 has been demonstrated to be a useful blood biomarker for detecting Alzheimer’s disease (AD) pathology. It has not been studied in Chinese population in real-world clinic.
Methods: 98 patients were recruited between 1st March to 19th July, 2024 from Memory Clinic of Queen Mary Hospital. Their plasma P-tau 217 levels were measured. Post-test probabilities (Bayesian approach) were calculated. The validation cohort (n=48) had amyloid positron emission tomography (PET) results available. They were used to determine the cut-offs of plasma P-tau 217 and post-test probabilities using the receiver operating curve (ROC) analysis. The cut-offs were then applied to the application cohort (n=50) without amyloid PET to study the clinical impact.
Results: Using single cut-off plasma P-tau 217 >10.08pg/ml, the sensitivity and specificity of the test was 86.67% and 88.89% respectively. After applying the cut-off in application cohort, 50% (19/38) of the clinically diagnosed AD patients were diagnosed as non-AD. 16.7% (2/12) of the clinically diagnosed non-AD patients were diagnosed as AD. Using a cut-off of >39.41% post-test probability showed a sensitivity of 93.33% and specificity of 88.89% respectively. Plasma P-tau 217 correlates with Neuropsychiatric Inventory Scores (NPI) (correlation coefficient 0.42, 95% CI 0.12-0.65, p=0.01), dysphoria subscores (correlation coefficient 0.49, 95% CI 0.2-0.70, p=0.001) and apathy subscores (correlation coefficient 0.38, 95% CI 0.06-0.62, p=0.02) in plasma P-tau 217 defined AD patients.
Conclusions: Plasma P-tau 217 is useful in diagnosing AD in Chinese population with cognitive impairment. It correlates with NPI in plasma P-tau 217 defined AD patients.