Independent study demonstrates amyloid probability score accurately indicates amyloid pathology

Abstract

Background:The amyloid probability score (APS) is the model read-out of the analytically validated mass spectrometry-based PrecivityAD â blood test that incorporates the plasma Ab42/40 ratio, ApoE proteotype, and age to identify the likelihood of brain amyloid plaques among cognitively impaired individuals being evaluated for Alzheimer's disease. Purpose: This study aimed to provide additional independent evidence that the pre-established APS algorithm, along with its cutoff values, discriminates between amyloid positive and negative individuals. Methods: The diagnostic performance of the PrecivityAD test was analyzed in a cohort of 200 nonrandomly selected Australian Imaging, Biomarker & Lifestyle Flagship Study of Aging (AIBL) study participants, who were either cognitively impaired or healthy controls, and for whom a blood sample and amyloid PET imaging were available. Results: In a subset of the dataset aligned with the Intended Use population (patients aged 60 and older with CDR ≥0.5), the pre-established APS algorithm predicted amyloid PET with a sensitivity of 84.9% (CI: 72.9-92.1%) and specificity of 96% (CI: 80.5-99.3%), exclusive of 13 individuals for whom the test was inconclusive. Interpretation: The study shows individuals with a high APS are more likely than those with a low APS to have abnormal amounts of amyloid plaques and be on an amyloid accumulation trajectory, a dynamic and evolving process characteristic of progressive AD pathology. Exploratory data suggest APS retains its diagnostic performance in healthy individuals, supporting further screening studies in the cognitively unimpaired.

Clinical validation of the PrecivityAD2 blood test: A mass spectrometry‐based test with algorithm combining %p‐tau217 and Aβ42/40 ratio to identify presence of brain amyloid

“…We used the same method for validating the PrecivityAD test, and that algorithm has since shown external validation in an orthogonal set of samples. 25 More studies are under way that seek to further demonstrate the robust clinical performance and generalizability of the APS2 model.…”

A blood biomarker test for brain amyloid impacts the clinical evaluation of cognitive impairment

“…A clinically and analytically validated mass spectrometry blood test and an algorithm combining Aβ42/40 ratio, ApoE proteotype and age (PrecivityAD blood test) variables yielding the APS has been previously described. 9 , 10 , 11 , 14 The main validation paper was focused on a cohort study that included analysis from two independent cross‐sectional cohort studies: the PARIS study, a prospective add‐on subset ( n = 249) to the Imaging Dementia–Evidence for Amyloid Scanning study (ClinicalTrials.gov Identifier: NCT02420756 ) as well as the cohort ( n = 437) of the MissionAD study (ClinicalTrials.gov Identifier: NCT02956486 ) who underwent amyloid PET testing. The reference standard used in this analysis was the presence or absence of brain amyloid on amyloid PET scan.…”

“…A more recently published analysis based on an independent cohort of participants from the Australian Imaging, Biomarker & Lifestyle Flagship Study of Ageing (AIBL) demonstrated that the PrecivityAD blood test with its validated, established cutoff values maintained high diagnostic accuracy for identifying the presence of absence of brain amyloid plaques. 11 In addition, two recent studies that evaluated the combination of plasma Aβ42/Aβ40 and APO Eε4 as well as the BBM combination plus age showed high correspondence with amyloid PET and provided Class II evidence that plasma Aβ42/Aβ40 levels accurately determine amyloid PET status. 12 , 13 …”

Executive Summary of 2023 International Conference of the Korean Dementia Association (IC-KDA 2023): A Report From the Academic Committee of the Korean Dementia Association

“…These tests showed the significant reliability of measuring brain amyloid plaques in individuals aged 55 and older with cognitive impairment. 8 9 His presentation also addressed the integration of blood biomarkers into routine clinical care, emphasizing diagnostic accuracy, clinical usefulness, and economic considerations in shaping the future role of blood biomarkers in cognitive care and management.…”