title: Comparison of cerebrospinal fluid levels of tau and Aβ 1-42 in Alzheimer disease and frontotemporal degeneration using 2 analytical platforms.
abstract: OBJECTIVE
  To use values of cerebrospinal fluid tau and β-amyloid obtained from 2 different analytical immunoassays to differentiate Alzheimer disease (AD) from frontotemporal lobar degeneration (FTLD).
  
  
  METHODS
  Cerebrospinal fluid values of total tau (T-tau) and β-amyloid 1-42 (Aβ 1-42) obtained using the Innotest enzyme-linked immunosorbent assay were transformed using a linear regression model to equivalent values obtained using the INNO-BIA AlzBio3 (xMAP; Luminex) assay. Cutoff values obtained from the xMAP assay were developed in a series of autopsy-confirmed cases and cross validated in another series of autopsy-confirmed samples using transformed enzyme-linked immunosorbent assay values to assess sensitivity and specificity for differentiating AD from FTLD.
  
  
  METHODS
  Tertiary memory disorder clinics and neuropathologic and biomarker core centers.
  
  
  METHODS
  Seventy-five samples from patients with cerebrospinal fluid data obtained from both assays were used for transformation of enzyme-linked immunosorbent assay values. Forty autopsy-confirmed cases (30 with AD and 10 with FTLD) were used to establish diagnostic cutoff values and then cross validated in a second sample set of 21 autopsy-confirmed cases (11 with AD and 10 with FTLD) with transformed enzyme-linked immunosorbent assay values.
  
  
  METHODS
  Diagnostic accuracy using transformed biomarker values.
  
  
  RESULTS
  Data obtained from both assays were highly correlated. The T-tau to Aβ 1-42 ratio had the highest correlation between measures (r = 0.928, P < .001) and high reliability of transformation (intraclass correlation coefficient= 0.89). A cutoff of 0.34 for the T-tau to Aβ 1-42 ratio had 90% and 100% sensitivity and 96.7% and 91% specificity to differentiate FTLD cases in the validation and cross-validation samples, respectively.
  
  
  CONCLUSIONS
  Values from 2 analytical platforms can be transformed into equivalent units, which can distinguish AD from FTLD more accurately than the clinical diagnosis.
authors.affiliation: Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Institute on Aging, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Irwin
authors.forename: Corey T
authors.initials: CT
authors.lastname: McMillan
authors.forename: Jon B
authors.initials: JB
authors.lastname: Toledo
authors.forename: Steven E
authors.initials: SE
authors.lastname: Arnold
authors.forename: Leslie M
authors.initials: LM
authors.lastname: Shaw
authors.forename: Li-San
authors.initials: LS
authors.lastname: Wang
authors.forename: Vivianna
authors.initials: V
authors.lastname: Van Deerlin
authors.forename: Virginia M-Y
authors.initials: VM
authors.lastname: Lee
authors.forename: John Q
authors.initials: JQ
authors.lastname: Trojanowski
authors.forename: Murray
authors.initials: M
authors.lastname: Grossman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000134:cerebrospinal fluid* / Q000175:diagnosis*; D016229:Amyloid beta-Peptides / Q000134:cerebrospinal fluid*; D015415:Biomarkers / Q000134:cerebrospinal fluid; D004797:Enzyme-Linked Immunosorbent Assay / Q000592:standards; D005260:Female; D057174:Frontotemporal Lobar Degeneration / Q000134:cerebrospinal fluid* / Q000175:diagnosis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000134:cerebrospinal fluid*; D016875:tau Proteins / Q000134:cerebrospinal fluid*
chemical_list: D016229:Amyloid beta-Peptides; D015415:Biomarkers; D010446:Peptide Fragments; C075222:amyloid beta-protein (1-42); D016875:tau Proteins