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Alzheimer’s disease CSF biomarker assays: Impact of methodology changes in clinical practice
Author(s) -
Campbell Michelle R.,
Kian Susan Ashrafzadeh,
Petersen Ronald C.,
Bornhorst Joshua A,
AlgecirasSchimnich Alicia
Publication year - 2021
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1002/alz.051426
Subject(s) - concordance , medicine , cerebrospinal fluid , roche diagnostics , clinical practice , pathological , pathology , biomarker , dementia , disease , gastroenterology , nuclear medicine , oncology , family medicine , chemistry , biochemistry
Background Decreased amyloid β 1‐42 (Aβ42) and increased tau (t‐Tau and p‐Tau) concentrations in cerebrospinal fluid (CSF) reflect the pathological changes of Alzheimer’s disease (AD) and aid in the diagnosis of AD dementia. In the United States, the ADmark® assay has been almost exclusively used for the measurement of these biomarkers in clinical practice. Recently, our institution switched from the ADmark® assay to the Roche Elecsys assays. The goal of this study was to determine if differences exist between these methods in classification of patients as having changes indicative of AD pathology. Method Patients undergoing ADMark® testing (n= 73) were recruited to participate in this IRB‐approved study. Two simultaneous CSF aliquots were obtained. For ADMark®, 2.0mL were collected into a 5mL polypropylene (PP) tube and shipped frozen to Athena Diagnostics per collection instructions for testing (Innotest® immunoassays for Aβ42, t‐Tau, and p‐Tau). For the Roche Elecsys assays (Aβ42, t‐Tau, and p‐Tau), 2.0mL were collected into a 2.5mL low bind PP tube, frozen, and then tested at Mayo Clinic Laboratories. Comparative analysis was performed between the two testing methodologies and to clinical findings. Result Overall concordance between the ADMark® Aβ42/t‐Tau index (ATI) and Roche p‐Tau/Aβ42 was 89% with 8 (11%) discrepant cases. Four cases were classified as normal by the Roche p‐Tau/Aβ42 but borderline (n=3) or abnormal (n=1) by ADMark® ATI. Four cases were classified as abnormal by the Roche p‐Tau/Aβ42 and borderline by ADMark® ATI. In these cases, the normal Roche p‐Tau/Aβ42 result was most consistent with clinical diagnosis. When compared to clinical diagnosis, cases with clinical suspicion of AD dementia were abnormal in 84% and 92% of cases with the ADMark® ATI and the Roche p‐Tau/Aβ42, respectively. In cases without clinical suspicion of AD dementia, results were abnormal in 19% and 21% of cases with the ADMark® ATI and the Roche p‐Tau/Aβ42, respectively. There were 2 cases with clinical suspicion of AD dementia and 5 cases without suspicion of AD dementia that were classified as borderline by ADMark® ATI. Conclusion Roche p‐Tau/Aβ42 showed comparable performance to ADMark® ATI when correlating results to clinical diagnosis of AD dementia.