Application of PrecivityAD™ Plasma Amyloid Beta Test in Clinical Practice

Valory Pavlik, Ph.D., Chi-Ying, Roy Lin, M.D., Joseph Kass M.D., Shayla Yonce, B.A., Laxmi Gaudel, B.S.,

Baylor College of Medicine 

Introduction

Gold standard for diagnosing Alzheimer’s disease (AD) pathology in clinical practice is a positive amyloid pet scan or abnormal CSF biomarkers. These procedures are costly, inconvenient, and/or not widely available.

•Plasma-based biomarker tests that predict amyloid positivity could aid in clinical decision making in early symptomatic phases of Alzheimer’s disease and other dementias.

•PrecivityAD™, a first generation plasma biomarker test produced by C2N Diagnostics, reports the probability of amyloid positivity derived from a regression equation that includes the plasma Aβ42/40 ratio, age, and APOE genotype.

•An AUC-ROC of .90 and overall accuracy of .86 reported (West et al., Molecular Neurodegeneration 2021;16:30.) 

•Amyloid positivity probability score categorized as High, Intermediate, or Low.  Intermediate score requires further testing.  

Objective

To evaluate the ability of PrecivityAD™to predict AD pathology and 2-year disease progression in clinical practice 

Methods

•Setting: Academic memory clinic staffed by two neurologists and a Physician’s Assistant

•Eligible Participants:Patients with mild symptoms undergoing initial assessment with

oMMSE ≥22

oCDR global score ≤ 1

oA presumptive diagnosis of subjective memory complaint, mild cognitive impairment (MCI), or probable AD

•Consensus clinical diagnosis following NIA-AA criteria assigned prior to obtaining PrecivityAD™result 

•Results of subsequent confirmatory amyloid testing recorded and compared to PrecivityAD™score predictions

•Logisitcregression use to assess probability of disease progression over two years by PrecivityAD™ amyloid probability score