title: Predictive value of antinuclear antibodies in autoimmune diseases classified by clinical criteria: Analytical study in a specialized health institute, one year follow-up.
abstract: BACKGROUND
  Determination of antinuclear antibodies (ANA) by indirect immunofluorescence (IIF) is usually the initial test for the diagnosis of systemic rheumatic diseases (SRD). Assigning predictive values to positive and negative results of the test is vital because lack of knowledge about ANAs and their usefulness in classification criteria of SRD leads to inappropriate use.
  
  
  METHODS
  Retrospective study, ANA tests requested by different specialties, correlation to patients' final diagnosis.
  
  
  RESULTS
  The prevalence of autoimmune disease was relatively low in our population yielding a low PPV and a high NPV for the ANA test. 40% of the patients had no clinical criteria applied prior to test. Coexistence of two or more autoimmune disorders affects prevalence and predictive values.
  
  
  CONCLUSIONS
  Application of the test after careful evaluation for clinical criteria remarkably improves the positive likelihood ratio for the diagnosis.
authors.affiliation: Department of Immunology, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, Mexico.
authors.forename: María Elena
authors.initials: ME
authors.lastname: Soto
authors.affiliation: Department of Immunology, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, Mexico.
authors.forename: Nidia
authors.initials: N
authors.lastname: Hernández-Becerril
authors.affiliation: Department of Immunology, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, Mexico.
authors.forename: Ada Claudia
authors.initials: AC
authors.lastname: Perez-Chiney
authors.affiliation: Department of Immunology, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, Mexico.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Hernández-Rizo
authors.affiliation: Universidad Panamericana School of Medicine, Mexico City, Mexico.
authors.forename: José Eduardo
authors.initials: JE
authors.lastname: Telich-Tarriba
authors.affiliation: Universidad Nacional Autónoma de México, Faculty of Medicine, Mexico City, Mexico.
authors.forename: Luis Eduardo
authors.initials: LE
authors.lastname: Juárez-Orozco
authors.affiliation: Department of Cardiovascular Magnetic Resonance, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, Mexico.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Melendez
authors.affiliation: Department of Immunology, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, Mexico ; Department of Health Care, Universidad Autónoma Metropolitana-Xochimilco, Mexico City, Mexico.
authors.forename: Rafael
authors.initials: R
authors.lastname: Bojalil
keywords: Antinuclear antibodies; Clinical criteria; Generalized rheumatic disease; Predictive value.