title: Anti-cyclic citrullinated peptide autoantibodies measured by an automated enzyme immunoassay: analytical performance and clinical correlations.
abstract: BACKGROUND
  Autoantibodies against cyclic citrullinated peptide (anti-CCP) are considered to be a sensitive and specific marker for rheumatoid arthritis (RA). This study evaluated the analytical performance and clinical correlation of an automated enzyme immunoassay (DSX, DINEX Technologies), for the detection of anti-CCP autoantibodies (DIASTAT anti-CCP, Axis-Shield, DUNDEE UK).
  
  
  METHODS
  Commercial controls and serum pools were used to determine its precision, analytical sensitivity, functional sensitivity and linearity. Sera from 83 patients with established RA and from 140 controls, including patients with various autoimmune diseases, viral infections and cancer, as well as sex- and age-matched healthy subjects, were studied. The rheumatoid factor (RF) was also assayed in each sample, and the results were compared to the anti-CCP findings.
  
  
  RESULTS
  The total imprecision (CV%) was 4.7-7.2% for concentrations ranging between 1.98 and 71.81 U/mL. The lower detection limit was 0.038 U/mL. At a cut-off of 5 U/mL, the sensitivity and specificity for RA were 67.5% and 99.3%, respectively. The RF had a sensitivity of 66.3% and a lower specificity 82.1% than anti-CCP. When the two antibodies were used together, the specificity was 99.1%.
  
  
  CONCLUSIONS
  The anti-CCP assay we examined on a fully automated system showed a good analytical performance (analytical and functional sensitivity, linearity) and good clinical correlation. We conclude that this system can provide rapid, useful data.
authors.affiliation: Unità Operativa di Patologia Clinica I, Policlinico di Bari, Piazza G. Cesare 11, 70100 Bari, Italy. mtampoia@libero.it
authors.forename: Marilina
authors.initials: M
authors.lastname: Tampoia
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Brescia
authors.forename: Antonietta
authors.initials: A
authors.lastname: Fontana
authors.forename: Piera
authors.initials: P
authors.lastname: Maggiolini
authors.forename: Giovanni
authors.initials: G
authors.lastname: Lapadula
authors.forename: Nicola
authors.initials: N
authors.lastname: Pansini
mesh_terms: D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000097:blood*; D001331:Automation; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques / Q000295:instrumentation* / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010456:Peptides, Cyclic / Q000276:immunology*; D012680:Sensitivity and Specificity
chemical_list: D001323:Autoantibodies; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide