Session Information
Date: Sunday, November 8, 2015
Title: Systemic Lupus Erythematosus - Clinical Aspects and Treatment Poster Session I
Session Type: ACR Poster Session A
Session Time: 9:00AM-11:00AM
Background/Purpose:
A positive ANA test is a diagnostic criterion for several rheumatic diseases, although it may appear in other autoimmune disorders and healthy individuals. An ideal diagnostic test should be both specific and sensitive. Current recommendations from ACR suggest ANA done by IIF in Hep-2 cells as an initial test to investigate autoimmunity and anti-ENA are only recommended for patients who test positive for ANA. However, there is scarce evidence of the advantages of this practice versus focalized auto-antibody evaluation according to clinical suspicion. ANA negative lupus has been reported at 5%, these patients test positive for anti-Ro/SSA and/or anti-La/SSB.
We aimed to establish the sensitivity of ANA to detect anti-Ro/SSA antibodies since we consider this stepwise approach might lead to sub diagnosing patients.
Methods: We reviewed immunological studies sent to Quest Diagnostics between January 2010 up to December 2014. Inclusion criteria were patients who had both ANA and anti-Ro/SSA done simultaneously; we excluded patients in which any one of those were missing. We obtained the sensitivity of ANA for detection of anti-Ro/SSA.
Results:
In total 900 tests were reviewed. Both ANA by IIF and anti-Ro/SSA by ELISA were done in 499 patients of whom 71 patients (14.22%) had positive anti-SSA. Of these, 33 patients (46.47%) had positive ANA and 38 patients (53.53%) had negative ANA. Considering presence of ANA at any titer as positive, sensitivity of the test was 77.5%; considering ANA positive with a titer of at least 1:320 sensitivity decreased to 46.5%.
Conclusion: The ACR recommendations of evaluating for rheumatic disease with ANA exclusively are based on cost-efectiveness more than evidence. We found a sensitivity of 77.5% at best considering any titer as positive. According to our findings 22.5% to 53.5% of individuals with positive anti-Ro/SSA could go undetected. We find the ANA test to be a poor initial test to investigate for the presence of anti-Ro/SSA antibodies. Our most important limitation is our sample size, another one is that actual autoimmune disease could not be confirmed since we did not have access to clinical data; however our findings warrant further investigation. The ANA test done by Hep-2 has a lower sensitivity in detecting anti-Ro/SSA than that reported in the literature, making it a poor screening test in patients suspected to have rheumatic disease associated with anti-Ro/SSA antibodies. Changes in the proposed diagnostic algorithm may be at hand.
References
1. Nossent H y Rekvig OP. Antinuclear antibody screening in this new millennium: farewell to the microscope?. Scand J Rheumatol 2001;30:123-6.
2. Sugisaki K, Takeda I, Kanno T, et al. An anti-nuclear antibody-negative patient with systemic lupus erythematosus accompanied with anti-ribosomal P antibody. Intern Med 2002;41:1047-51.
3. Solomon DH, Kavanaugh AJ, Schur PH, Evidence-Based Guidelines for the Use of Immunologic Tests: Antinuclear Antibody Testing Arthritis & Rheumatism (Arthritis Care & Research) Vol. 47, No. 4, August 15, 2002, pp 434–444.
To cite this abstract in AMA style:
Alcantara-Arreola I, Tello-Winniczuk N, Diaz-Borjon A. Sensitivity of Antinuclear Antibody By Immunofluorescence Testing for Detection of Anti-Ro/SSA Antibodies [abstract]. Arthritis Rheumatol. 2015; 67 (suppl 10). https://acrabstracts.org/abstract/sensitivity-of-antinuclear-antibody-by-immunofluorescence-testing-for-detection-of-anti-rossa-antibodies/. Accessed .« Back to 2015 ACR/ARHP Annual Meeting
ACR Meeting Abstracts - https://acrabstracts.org/abstract/sensitivity-of-antinuclear-antibody-by-immunofluorescence-testing-for-detection-of-anti-rossa-antibodies/