Interpretation

Negative: A normal (negative) phosphorylated Tau217 (p-Tau217) result is consistent with a negative (normal) amyloid-positron emission tomography (PET) scan result. This result indicates a reduced likelihood that an individual has neuropathological changes associated with Alzheimer disease.

Intermediate: An intermediate p-Tau217 result cannot accurately differentiate between the presence or absence of neuropathological changes associated with Alzheimer disease. Further testing, such as amyloid-positron emission tomography (PET) or cerebrospinal fluid Abeta42 and tau biomarkers, is needed to determine the likelihood of neuropathological changes associated with Alzheimer disease being present.

Positive: An elevated (positive) p-Tau217 result is consistent with a positive (abnormal) amyloid-positron emission tomography (PET) scan result. This result is consistent with the presence of neuropathological changes associated with Alzheimer disease. In the proper clinical context this test is supportive of Alzheimer disease being related to current clinical symptoms. This test has not been demonstrated to provide information on the risk of an asymptomatic individual developing symptoms related to Alzheimer disease in the future.

Clinical performance of this test was established in a study of 427 individuals aged 50 years and older with mild cognitive impairment or early dementia with a 64% prevalence of amyloid pathology defined by an amyloid-PET and a Centiloid scale value of 25 or more. For detection of an abnormal amyloid-PET, pTau217 test sensitivity at the lower cutpoint (≤0.185 pg/mL) was 92% and the specificity at the upper cutpoint (≥0.325 pg/mL) was 96%. The diagnostic performance of this test has not been established in asymptomatic individuals.