Predictive value of antinuclear antibodies in autoimmune diseases classified by clinical criteria: Analytical study in a specialized health institute, one year follow-up

María Elena Soto,Nidia Hernández-Becerril,Ada Claudia Perez-Chiney,Alfredo Hernández-Rizo,José Eduardo Telich-Tarriba,Luis Eduardo Juárez-Orozco,Gabriela Melendez,Rafael Bojalil

doi:10.1016/j.rinim.2013.10.003

Abstract

Introduction: 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. Conclusion: Application of the test after careful evaluation for clinical criteria remarkably improves the positive likelihood ratio for the diagnosis.

Highlights

Determination of antinuclear antibodies (ANA) by indirect immunofluorescence (IIF) is usually the initial test for the diagnosis of systemic rheumatic diseases (SRD)
Further evaluated by more specific tests such as ELISA, radioimmunoanalysis (RIA) or electroimmunotransference (EIT) [2,4]. The use of these tests requires knowledge of their fundamental aspects and of the clinical classification criteria of each disorder in order to contribute to an appropriate diagnosis [5,6]. The usefulness of this testing has been evaluated in retrospective studies of patients with systemic rheumatic disease (SRD), and it has been proven that its positive predictive value is low due to the relatively large amount of false positive results
In 364 (83%) samples, nuclear antibodies were found with dilutions 1:40 and no antibodies were found in 9 cases (2%)

Summary

Introduction

Determination of antinuclear antibodies (ANA) by indirect immunofluorescence (IIF) is usually the initial test for the diagnosis of systemic rheumatic diseases (SRD). Further evaluated by more specific tests such as ELISA, radioimmunoanalysis (RIA) or electroimmunotransference (EIT) [2,4] The use of these tests requires knowledge of their fundamental aspects and of the clinical classification criteria of each disorder in order to contribute to an appropriate diagnosis [5,6]. The usefulness of this testing has been evaluated in retrospective studies of patients with systemic rheumatic disease (SRD), and it has been proven that its positive predictive value is low due to the relatively large amount of false positive results. This situation conveys challenges such as interpretative standardization [13]

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Conclusion