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Georgetown study: Scleroderma dramatically under-diagnosed with commercial screening method

08.11.2010
New research from Georgetown University Medical Center (GUMC) suggests that up to 40 percent of scleroderma patients will not be correctly diagnosed with the disorder using a new automated commercial screening test.

The findings of the study will be presented Wednesday, November 10th at the Annual Scientific Meeting of the American College of Rheumatology in Atlanta, Georgia.

The American College of Rheumatology recommends immunofluorescence antinuclear antibody (IF-ANA) testing to help detect the presence of scleroderma specific antinuclear antibodies. Finding the antibodies is a helpful predictor of disease manifestations, clinical course and outcome in scleroderma. However, many commercial labs have recently adopted a newer, automated method that use non-immunofluorescence antinuclear antibody testing. This test is known as NEW ANA.

To test the accuracy of the commercial method for detecting scleroderma antibodies, GUMC researchers evaluated the all test results performed through commercial laboratories of more than 200 scleroderma patients treated in the Georgetown scleroderma clinic between June 2008 and June 2009.

Test results using NEW ANA were available in 58 scleroderma patients. Twenty-eight patients (48 percent) tested negative. Of these 28 patients, 22 had either positive results using IF-ANA or one of the scleroderma specific antibodies. "The NEW ANA testing, that is the ANA test without immunofluorescence, failed to identify patients with a particular subset of scleroderma specific antinuclear antibodies and other patterns that are picked up with IF ANA testing. This finding was significant," says Victoria K Shanmugam, MBBS, MRCP, assistant professor in the Division of Rheumatology, Immunology and Allergy who presented the findings.

NEW ANA test results were not available for the remaining 183 scleroderma patients. IF ANA testing was conducted in these patients and the positive antibody results were divided by subtypes.

"Given what we know about the subsets that are not detected by the NEW ANA testing, it appears that as many as 40 percent of the scleroderma patients would have tested negative using the new commercial testing method," Shanmugam says. "If a clinician has clinical suspicion for scleroderma, they should order the immunofluorescent ANA."

Shanmugam's research is funded by the American College of Rheumatology, Research and Education Foundation, Physician Scientist Development Award and from the National Center for Research Resources.

The authors report no potential financial interests.

About Georgetown University Medical Center

Georgetown University Medical Center is an internationally recognized academic medical center with a three-part mission of research, teaching and patient care (through MedStar Health). GUMC's mission is carried out with a strong emphasis on public service and a dedication to the Catholic, Jesuit principle of cura personalis -- or "care of the whole person." The Medical Center includes the School of Medicine and the School of Nursing and Health Studies, both nationally ranked, the world-renowned Georgetown Lombardi Comprehensive Cancer Center and the Biomedical Graduate Research Organization (BGRO). In fiscal year 2009-2010, GUMC accounted for 79 percent of Georgetown University's extramural research funding.

Podium presentation: Wednesday, November 10, 2010, 5:45 pm

Abstract: [2197] - Antinuclear Antibody Screening in Systemic Sclerosis.

Donna Rose Swistowski, MD1,Nicole Saddic, MD2,Victoria K Shanmugam, MBBS, MRCP3,Virginia D Steen, MD4. 1Georgetown University Division of Rheumatology, Immunology, and Allergy, Bethesda, MD,2Georgetown University Hospital Department of Medicine,3Georgetown University Division of Rheumatology, Immunology, and Allergy,4Department of Rheumatology, Georgetown University Medical Center, Washington, DC

Purpose: Scleroderma specific antinuclear antibodies (SScAB) are helpful predictors of disease manifestations, clinical course and outcome in scleroderma. Historically, immunofluorescence (IF) antinuclear antibody (ANA) testing was the gold standard method for ANA detection, and the American College of Rheumatology continues to recommend IF for evaluation of ANA. Many commercial labs have recently adopted newer, automated, non-immunofluorescence methods (NEW ANAs), such as EIA (enzyme immunoassay) or immunobead methods to evaluate for the presence of antinuclear antibodies. These new techniques rely on a limited panel of autoantigens in the assay.

The purpose of this study was to evaluate ANAs and SScAB results performed through commercial labs, using both NEW ANA detection techniques and traditional IF, in a consecutive cohort of scleroderma patients seen in the Georgetown Scleroderma Clinic over a one year period.

Methods: Between June 2008 and June 2009, 241 scleroderma patients were evaluated. Patient charts were reviewed for results of NEW ANA, IF-ANA, isolated nucleolar ANA pattern (NuANA), and the SScAB profile including anticentromere (ACA), anti-topoisomerase (Scl-70), U1 RNP, and RNA polymerase III (Pol III) antibodies.

Results: The results of this study are summarized in table 1. NEW ANA results were available in 58 patients with 28 patients (48%) testing negative. Of these 28 patients, 22 had either positive IF-ANA or a SScAB recorded: IF-ANA only (n=7), NuANA (n=6), Pol III (n=7), SSB (n=1), U1 RNP (n=1). In the patients with a positive NEW ANA (n=30) the NEW ANA successfully detected all patients with ACA (n=4), Scl-70 (n=13), UI RNP (n=6), and SSA (n=1) antibodies. A positive NEW ANA additionally identified Pol III (n=1), NuANA with a + SSA (n=3), and nonspecific ANA (n=2). However, the NEW ANA failed to identify the NuANA, Pol III antibodies, and other IF-ANA patterns in a significant number of patients (20/22 vs. 6/30, p

The remaining 183 SSc patients did not have NEW ANA testing available. Of these patients, 156 (85%) had positive SScABs or an IF-ANA. ACA was present in 22.4%, Scl-70 in 25%, and U1 RNP in 9.6%. This accounts for 57% of patients who we predict would be identified with the NEW ANA assay. However, patients with other antibodies including Pol III (10.2%), NuANA (19.2%), and nonspecific ANA patterns (13.5%), account for 40% of the scleroderma patients in our population, and we predict these patients would not be identified using NEW ANA assays.

Conclusions: Immunofluorescence ANA should be performed in all patients in whom there is clinical suspicion for scleroderma. Physicians should remain skeptical of negative ANAs in patients with clinical evidence of scleroderma.

Karen Mallet | EurekAlert!
Further information:
http://www.georgetown.edu

Further reports about: ACA Allergy GUMC Georgetown IF-ANA Immunology MBBS Medical Wellness NuANA RNA Pol II RNP Rheumatology Scl-70 health services scleroderma

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