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The importance of detecting anti-DFS70 in routine clinical practice: comparison of different care settings

Authors
  • Bonroy, Carolien
  • Schouwers, Sofie
  • Berth, Mario
  • Stubbe, Muriel
  • Piette, Yves
  • Hoffman, Ilse
  • Devreese, Katrien
  • Van Hoovels, Lieve
Type
Published Article
Journal
Clinical Chemistry and Laboratory Medicine (CCLM)
Publisher
Walter de Gruyter GmbH
Publication Date
Feb 10, 2018
Volume
56
Issue
7
Pages
1090–1099
Identifiers
DOI: 10.1515/cclm-2017-0541
Source
De Gruyter
Keywords
License
Yellow

Abstract

Background: Screening for antinuclear antibodies by indirect immunofluorescence (ANA-IIF) is essential in the diagnostic workup of ANA-associated autoimmune rheumatic diseases (AARDs). However, also healthy individuals may test positive, making the interpretation challenging. Recent reports suggest that dense fine speckled 70 antibodies (anti-DFS70) may facilitate this challenge. Here, we investigate their clinical importance based on data from four Belgian laboratories (one primary, two secondary and one tertiary care). Methods: At least one specific DFS70 assay (DFS70 IgG ELISA or lineblot [Euroimmun, full length antigen] and/or DFS70 IgG CLIA [Inova Diagnostics, truncated antigen]) was performed on four consecutive cohorts of homogeneous-like ANA-IIF samples (n=697). Co-occurrence with AARD-specific ANA and clinical information were documented in the anti-DFS70-positive samples. Results: Using a combination of solid phase techniques, we found between 7.6% and 26% anti-DFS70 in the different cohorts. Focusing on anti-DFS70 CLIA-positive samples without co-occurrence of AARD-specific ANA, we observed a trend towards lower frequency in tertiary (8% [p=0.0786]) and secondary care (12% [p=0.1275] and 6% [p<0.001]) compared to primary care (21%). Moreover, in this specific subpopulation, AARD was less frequent (0%–50% compared to 6%–77% in the total anti-DFS70-positive group). Conclusions: Anti-DFS70 prevalence depends on the applied assay and care setting. Our data suggest that, for an ANA-IIF-positive patient, it is rather the absence of AARD-associated ANA and clinical symptoms that contribute to the exclusion of AARD than the presence of anti-DFS70. Nevertheless, isolated anti-DFS70 helps to clarify positive ANA-IIF results, especially if pretest probability for AARD is low.

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