C2N Diagnostics, a brain health diagnostics provider, says new research posted in the online version of Annals of Clinical and Translational Neurology affirms the clinical utility of its PrecivityAD blood test, which healthcare providers use to help diagnose Alzheimer’s disease (AD). 

The findings represent prospective, published evidence that clinicians use novel blood biomarker testing in a way that improves patient care management, the company says.

The Quality Improvement and Clinical Utility PrecivityAD Clinician Survey was a prospective, single-arm cohort study among 366 patients evaluated by 43 neurologists and other cognitive specialists in 15 academic centers and group practice sites. The authors of the journal article, “A Blood Biomarker Test for Brain Amyloid Impacts the Clinical Evaluation of Cognitive Impairment,” outline that the findings may have added relevance as drugmakers introduce new AD therapies.

Using the PrecivityAD Blood Test for Alzheimer’s Diagnostics

The PrecivityAD blood test’s Amyloid Probability Score (APS) represents the estimated likelihood from 0 (low likelihood) to 100 (high likelihood) that a patient will be amyloid positive on amyloid PET imaging based on his or her Aβ42/40 ratio, age and Apolipoprotein E proteotype (equivalent to ApoE genotype). A positive amyloid PET scan is consistent with presence of amyloid plaques and an Alzheimer’s disease diagnosis. In the pioneering study, clinicians selected patients with signs and symptoms of cognitive impairment who were evaluated for Alzheimer’s disease and other causes of cognitive decline.

In addition, a 95% (347/366) concordance rate was noted between clinicians’ patient selection and the PrecivityAD test’s intended use criteria. In the final analysis, including the 347 patients (median age 75 years, 56% women), pre-specified test result categories incorporated 133 (38%) Low APS, 162 (47%) High APS and 52 (15%) Intermediate APS patients. Clinicians’ pre- and post-test Alzheimer’s diagnosis probability changed from 58% to 23% for Low APS patients and 71% to 89% in High APS patients (p<0.0001).

The clinicians reported Low APS patients to have a lower Alzheimer’s probability post-test and were less likely to manage these patients with AD drug therapy (a decrease of 46% (p<0.0001), consistent with ruling out AD. Clinicians reported High APS patients to have a higher Alzheimer’s probability post-test and were more likely to manage these patients with AD drug therapy, consistent with ruling in AD (anti-AD drug therapy increased by 57% in High APS patients (p<0.0001)).

Further reading: C2N Diagnostics’ Precivity-Related Blood Biomarkers Improve Alzheimer’s Diagnostic Accuracy

A literature review by the authors has shown that the current misdiagnosis rates for Alzheimer’s disease range from 30–50%. While amyloid positron emission tomography (PET) scans and cerebrospinal fluid (CSF) biomarkers substantially reduce misdiagnosis rates, their use is limited in routine clinical care due to high costs, logistic complexities, and patient burden.

“These data address a major gap in the further use of blood biomarkers in the real world, patient care setting. The CTAD 2022 Task Force Report and recent Alzheimer’s Association-National Institute on Aging draft guidelines underscore the use of prospective data and use of pre-specified endpoints, both of which were utilized in the QUIP I study,” says Joel B. Braunstein, MD, CEO of C2N Diagnostics. “Furthermore, the clinical utility data on the change in clinical decision-making associated with the PrecivityAD blood test results complement the previously published work on clinical validity and test performance of the PrecivityAD blood test.”

The authors state that larger trials with longer follow-up are desired to further understand the effect of the PrecivityAD blood test results on changes in diagnostic and management strategies as well as patient outcomes.

The PrecivityAD blood test is intended for use in individuals experiencing memory and thinking issues. The test is only available through an order by a healthcare provider. The test is available in 49 states, the District of Columbia, and Puerto Rico.