Real-world diagnostic performance of blood-based biomarkers for Alzheimer's disease: robust performance except after stroke and high charlson comorbidity index.

BACKGROUND: Accurate plasma biomarker interpretation is essential for diagnosing Alzheimer's disease (AD). This study evaluated how patient factors influence the association between plasma biomarkers and amyloid status in a memory clinic population. METHODS: A cross-sectional study of 1199 participants from the Amsterdam Dementia Cohort analysed plasma biomarkers (pTau217, pTau181, Aβ42/40, GFAP, NfL, and a combined panel) and patient factors (comorbidities, medication use, vital signs, body mass index, and kidney function). Amyloid status was determined via amyloid PET (n = 309) or CSF pTau181/Aβ1-42 (n = 890). RESULTS: Stroke, hypercholesterolemia, antidepressant use and Charlson Comorbidity Index (CCI) influenced biomarker performance. Stroke reduced the diagnostic value of pTau217, Aβ42/40 and the biomarker panel, while hypercholesterolemia and antidepressant use enhanced pTau217 and Aβ42/40, respectively. A CCI ≥ 2 reduced the biomarker panel's performance. CONCLUSIONS: Overall, patient factors had limited impact on biomarkers, but caution is needed for patients with stroke or high CCI.