Diagnostic Accuracy of Anti-dsDNA Antibodies in Unselected Patients with Recent Onset of Rheumatic Symptoms

Michele Compagno¹, Søren Jacobsen², Ole Petter Rekvig³, Lennart Truedsson⁴, Niels H. H. Heegaard⁵, Johannes C. Nossent⁶, Andreas Jönsen¹, Rasmus Sleimann Jacobsen⁷, Gro Østli Eilertsen⁶, Gunnar K. Sturfelt⁸ and Anders Bengtsson¹, ¹Department of clinical sciences - Rheumatology, Lund University, Lund, Sweden, ²Department of Rheumatology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark, ³Department of Biochemistry and Medical Biology, University Hospital, Tromsø, Norway, ⁴Department of Laboratory Medicine, Section of Microbiology, Immunology and Glycobiology, Lund University, Lund, Sweden, ⁵Department of Clinical Biochemistry, Immunology & Genetics, Statens Serum Institut, Copenhagen, Denmark, ⁶Dept of Rheumatology, University of Tromsø, Tromso, Norway, ⁷Department of Infectious Diseases and Rheumatology, Section 4242, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark, ⁸Department of Rheumatology, University Hospital Lund, Lund, Sweden

Meeting: 2012 ACR/ARHP Annual Meeting

Keywords: anti-dsDNA, autoantibodies, autoimmune diseases, laboratory tests and multicenter study

Session Information

Title: Systemic Lupus Erythematosus: Clinical Aspects

Session Type: Abstract Submissions (ACR)

Background/Purpose: Anti-dsDNA antibodies are widely used in diagnostic settings when SLE is suspected. Crithidia Luciliae Immunofluorescence Test (CLIFT) and Enzyme Linked ImmunoSorbent Assay (ELISA) are commonly used assays to detect anti-dsDNA antibodies in clinical practice. The aim of the present study was to evaluate the diagnostic accuracy of CLIFT and ELISA in unselected patients with recent onset of rheumatic symptoms.

Methods: In the three participating centres, 1073 consecutive patients were locally screened for ANA. A total of 292 ANA positive patients and 292 matching ANA negative patients were selected. Anti-dsDNA antibodies were assessed at study entry by different laboratories with CLIFT (totally four times using two different commercial kits) and with ELISA (totally four times with three different commercial kits). The results of the laboratory tests were related to the clinical diagnosis formulated at study entry and verified after a long term follow-up period (median 4.8 years).

Results: Discrepant results were obtained from the different assessments regardless of the assay used, with kappa statistics value ranging between 0.25 and 0.75. At least one anti-dsDNA analysis was positive in 164 patients, but in only seven patients the positivity was confirmed by all the assessments. SLE diagnosis was initially made in 65 patients, of which 40 were anti-dsDNA positive. A wide spectrum of other diagnoses was observed among anti-dsDNA positive patients. Overall, about one third of anti-dsDNA positive patients were ANA negative. At follow-up after approximately 5 years, SLE diagnosis was unchanged in 63 patients (39 anti-dsDNA positive) and changed in only two (one anti-dsDNA positive). Among the 120 anti-dsDNA positive patients not diagnosed with SLE at study entry, only one developed SLE during the follow-up period.

Conclusion: Regardless of the assay used, assessment of anti-dsDNA antibodies was not reliable as diagnostic tool in our cohort of unselected patients with rheumatic symptoms. ANA showed poor reliability as screening test before anti-dsDNA analysis. Anti-dsDNA antibodies had surprisingly low positive predictive value for SLE diagnosis, despite their high specificity. For non SLE patients, being anti-dsDNA positive poses little risk of developing SLE within 5 years.

Disclosure:

M. Compagno,
None;

S. Jacobsen,
None;

O. P. Rekvig,
None;

L. Truedsson,
None;

N. H. H. Heegaard,
None;

J. C. Nossent,
None;

A. Jönsen,
None;

R. Sleimann Jacobsen,
None;

G. Eilertsen,
None;

G. K. Sturfelt,
None;

A. Bengtsson,
None.

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