Scleroderma Test may not Provide Best Results

A new automated commercial screening test fails to correctly diagnose up to 40% of scleroderma patients, according to researchers from Georgetown University Medical Center (GUMC).

The findings are a result of a study that examined the accuracy of a newer, automated method that use non-immunofluorescence antinuclear antibody testing. This test is known as the NEW ANA test.

The American College of Rheumatology recommends using recommends immunofluorescence antinuclear antibody (IF ANA) testing. The test is designed to detect the presence of scleroderma specific antinuclear antibodies, which help predict disease manifestations, clinical course, and outcome in scleroderma.

To test the accuracy of the commercial method (NEW ANA), GUMC researchers evaluated 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%) 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,” said Victoria K Shanmugam, MBBS, MRCP, assistant professor in the Division of Rheumatology, Immunology and Allergy who presented the findings, in a press release.

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 said, in a press release. “If a clinician has clinical suspicion for scleroderma, they should order the immunofluorescent ANA.”

Source: Georgetown University Medical Center

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