C2N Diagnostics has published results from a clinical study showing that its PrecivityAD2 blood test can be used to screen for Alzheimer's disease in primary care settings.

The data was published in the Journal of the American Medical Association (JAMA) and will be presented at the Alzheimer's Association International Conference taking place in Philadelphia from 28 July to 1 August.

The PrecivityAD2 test demonstrated an accuracy of 90% in identifying Alzheimer’s in patients with memory loss, at a pre-defined, single binary cutoff compared to cerebrospinal fluid (CSF) analysis or amyloid PET analysis.

One of the study’s authors, Dr Oskar Hansson, noted that “primary care physicians diagnosed Alzheimer’s disease pathology accurately only 61% of the time when they relied on the standard of care involving a clinical examination, cognitive testing and a CT scan”.

The PreclivityAD2 test uses high-resolution mass spectrometry to precisely measure proteins in the blood that indicate the likelihood of amyloid plaques in the brain, a pathological hallmark of Alzheimer’s. The test relies on a validated algorithm that combines plasma Aβ42/40 and p-tau217/np-tau217 ratios to predict the likelihood of the presence of brain amyloid pathology. The Precivity blood tests are intended for use in patients aged 55 years and older with signs or symptoms of mild cognitive impairment or dementia who are undergoing evaluation for Alzheimer’s disease or dementia.

The study enrolled 1213 patients undergoing cognitive evaluation in primary or secondary care. The trial compared blood tests and the physicians’ estimation to a clinical, biomarker-verified Alzheimer’s disease diagnosis. Dementia specialists identified clinical Alzheimer's with a diagnostic accuracy of 73% compared to 91% using the APS2 while primary care physicians had a diagnostic accuracy of 61%.

“The test performed the same in primary care and speciality memory care, and it was highly accurate regardless of patients’ clinical presentation and medical comorbidities,” said C2N’s CEO and co-founder Dr Joel Braunstein.

“The outcomes should eliminate the need for invasive lumbar punctures and costly amyloid PET scans for most patients while also helping to reduce the time to an accurate diagnosis on a global scale.”

Multiple companies are developing diagnostic blood tests for Alzheimer’s. In April, Roche secured a breakthrough device designation from the US Food and Drug Administration for its Elecsys pTau217 plasma biomarker assay.