title: Predictive value of anti-citrullinated peptide antibodies: a real life experience.
abstract: Rheumatoid Arthritis (RA) is an autoimmune destructive joint disease, characterized by the presence of rheumatoid factor and anti-citrullinated peptide antibodies. Anti-citrullinated peptide antibodies were recently defined as RA criterion with sensitivity and specificity of 50-80 and 75-95 %, respectively. However, in the general population, the predictive value of anti-citrullinated peptide antibodies is yet to be determined. Herein, we aim to determine the predictive value of anti-citrullinated peptide antibodies in real life as well as clinical and serological factors related to this value. Retrospective cross-sectional study of consecutive samples evaluated for anti-citrullinated peptide antibodies in a referral autoimmune laboratory. Demographic and clinical parameters at the time the sample was drawn were collected. During November 2011 through December 2013, a total of 215 anti-citrullinated peptide antibody tests were performed in our laboratory. Data were available for 140 samples of which only 28 samples were positive for anti-citrullinated peptide antibodies. Of the 140 patients tested, 18 were diagnosed with RA, of which 12 were positive and 6 were negative for anti-citrullinated peptide antibody test. Thus, in this cohort, anti-citrullinated peptide antibodies were positive in 20 % of samples with a positive predictive value (PPV) of 43 % and a negative predictive value of 95 %. In real life, only 20 % of anti-citrullinated peptide antibody tests referred to a tertiary center where found to be positive. The negative predictive value of this test is very high and may support the common use of anti-citrullinated peptide antibody test as an exclusion criterion in the process of evaluating a patient with rheumatic disease.
authors.affiliation: The Zabludowicz Center for Autoimmune Diseases, Sheba Medical Center, Tel-Hashomer, Israel, watad.abdulla@gmail.com.
authors.forename: Abdulla
authors.initials: A
authors.lastname: Watad
authors.forename: Nancy
authors.initials: N
authors.lastname: Agmon-Levin
authors.forename: Boris
authors.initials: B
authors.lastname: Gilburd
authors.forename: Merav
authors.initials: M
authors.lastname: Lidar
authors.forename: Howard
authors.initials: H
authors.lastname: Amital
authors.forename: Yehuda
authors.initials: Y
authors.lastname: Shoenfeld
mesh_terms: D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000175:diagnosis* / Q000276:immunology*; D001323:Autoantibodies / Q000097:blood / Q000276:immunology*; D001324:Autoantigens / Q000276:immunology*; D002956:Citrulline / Q000276:immunology*; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010455:Peptides / Q000737:chemistry / Q000276:immunology*; D011379:Prognosis; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012217:Rheumatoid Factor / Q000097:blood / Q000276:immunology; D012680:Sensitivity and Specificity
chemical_list: D001323:Autoantibodies; D001324:Autoantigens; D010455:Peptides; D002956:Citrulline; D012217:Rheumatoid Factor