title: The AD-CSF-index discriminates Alzheimer's disease patients from healthy controls: a validation study.
abstract: BACKGROUND
  Cerebrospinal fluid (CSF) biomarkers of Alzheimer's disease (AD) show an acceptable diagnostic sensitivity and specificity; however, their interpretation and ease of use is far from optimal.
  
  
  OBJECTIVE
  To study and validate the diagnostic accuracy of an easy-to-use normalized CSF biomarker index, the AD-CSF-index, in different European populations.
  
  
  METHODS
  A total of 342 subjects, 103 healthy controls and 239 AD patients, from four European memory clinics were included. The AD-CSF-index was constructed from the addition of normalized values between the minimum and maximum of amyloid and tau protein levels. The diagnostic accuracy, receiver operating characteristic, and regression analysis of the AD-CSF-index and other composite indices were evaluated in this study.
  
  
  RESULTS
  AD patients presented a significantly higher AD-CSF-index than healthy subjects (control = 0.5204; AD = 1.2272; p < 0.001). The AD-CSF-index obtained a sensitivity of 88.6% at 85% specificity and also showed a significantly higher diagnostic power (p < 0.05) than the individual CSF biomarkers and other studied indices. The performance of the AD-CSF-index was very similar between ELISA and MesoScale measurements. Cut-off values of approximately 0.75 provided the lowest achievable overall classification errors and a cut-off point of about 0.95 consistently provided specificities above 85%.
  
  
  CONCLUSIONS
  The AD-CSF-index represents a novel approach, combining normalized CSF values, for the biological diagnosis of AD. The AD-CSF-index presents an optimal AUC with high sensitivity and specificity and seems to be a simple and intuitive way to interpret AD CSF biomarker results even from different analytical platforms.
authors.affiliation: Alzheimer's Disease and Other Cognitive Disorders Unit, Neurology Service, Hospital Clínic, Barcelona, Spain. jlmoli@clinic.ub.es
authors.forename: Jose L
authors.initials: JL
authors.lastname: Molinuevo
authors.forename: Juan Domingo
authors.initials: JD
authors.lastname: Gispert
authors.forename: Bruno
authors.initials: B
authors.lastname: Dubois
authors.forename: Michael T
authors.initials: MT
authors.lastname: Heneka
authors.forename: Alberto
authors.initials: A
authors.lastname: Lleo
authors.forename: Sebastiaan
authors.initials: S
authors.lastname: Engelborghs
authors.forename: Jesús
authors.initials: J
authors.lastname: Pujol
authors.forename: Leonardo Cruz
authors.initials: LC
authors.lastname: de Souza
authors.forename: Daniel
authors.initials: D
authors.lastname: Alcolea
authors.forename: Frank
authors.initials: F
authors.lastname: Jessen
authors.forename: Marie
authors.initials: M
authors.lastname: Sarazin
authors.forename: Foudil
authors.initials: F
authors.lastname: Lamari
authors.forename: Mircea
authors.initials: M
authors.lastname: Balasa
authors.forename: Anna
authors.initials: A
authors.lastname: Antonell
authors.forename: Lorena
authors.initials: L
authors.lastname: Rami
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000134:cerebrospinal fluid / Q000175:diagnosis*; D016229:Amyloid beta-Peptides / Q000134:cerebrospinal fluid; D015415:Biomarkers / Q000134:cerebrospinal fluid; D016022:Case-Control Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000134:cerebrospinal fluid; D012680:Sensitivity and Specificity; 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