AB1044 POSITIVE ANA TESTING IN AN ACADEMIC MEDICAL CENTER: IMPACT ON DIAGNOSIS
Authors: D. Karp, B. Bermas, S. Kottur
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> sAnti-nuclear antibodies (ANA) are common in systemic rheumatic diseases, non-rheumatic autoimmune diseases and the general population. In clinical practice, testing for ANA can inform further clinical diagnoses even in the absence of symptoms to suggest SLE or connective tissue disease. This study was undertaken to evaluate whether ANA testing result informed clinical diagnosis. <h3>Objectives:</h3> 1). Determine the frequency of ANA testing in an academic medical center, 2). Determine the demographics and principal diagnoses of people undergoing ANA testing in an academic medical center, and 3) Determine the impact of positive ANA determinations on diagnosis and patient care. <h3>Methods:</h3> The UT Southwestern Medical Center IRB approved this study. Data were obtained by SQL queries of the Epic electronic health record. The study population included all patients for whom an ANA was ordered at UT Southwestern Medical Center January 1, 2010 to June 30, 2017. The titer and pattern of the ANA as well as the results of ENA or anti-dsDNA testing were documented. Patient characteristics included age and sex. Encounter characteristics included the date of testing, frequency of testing, primary encounter diagnosis, and provider specialty. Chart review was performed by a board-certified rheumatologist in patients who had a change in diagnosis after a positive ANA. <h3>Results:</h3> During the study period, a total of 33,270 ANA tests were ordered in 28,659 unique patients. 22,529 of the ANAs were tested in outpatients, representing 0.7% of all office visits during this time. Forty-nine percent of the ANA tests were positive at a titer of 1:80 or greater; slightly more women (51%) had a positive ANA (≥1:80) than did men (43%). 54.5% of the positive ANA in women were 1:320 or greater vs. 41.6% in men (p&lt;0.0001). In 118 patients with a positive ANA, ICD 9 coding changed from a non-rheumatic disease diagnosis to a rheumatic disease diagnosis after ANA testing. Chart review showed that 26 of these patients had testing for joint pain. In 7 the note described this as inflammatory, while in 19 it was not specified. In five of the seven patients with a prior diagnosis of rheumatoid arthritis, the diagnosis was changed to SLE, and one was changed to Sicca syndrome. The 19 with non-inflammatory arthritis were diagnosed UCTD (7), with sicca or Sjögren's (6), drug induced SLE (1) and SLE (3) although none of these fulfilled the 2019 EULAR/ACR criteria. 16 patients had a prior diagnosis of SLE that was confirmed. 14 had a initial diagnosis of "positive ANA" and 13 had their diagnosis changed to a systemic rheumatologic disease (SLE, incomplete SLE, Sjögren's syndrome, UCTD, or systemic sclerosis). 9 patients had autoimmune liver disease confirmed and 8 had confirmed dermatomyositis. In 1 of 12 patients that carried a diagnosis of rheumatologic disorder (MCTD or Sjögrens) the diagnosis was changed to SLE while the other 11 had the diagnosis stay the same. In most of the remaining patients with either symptoms specific to SLE (pleurisy, pancytopenia, or non-specific hearing loss), the diagnosis was changed to UCTD or sicca syndrome. <h3>Conclusion:</h3> ANA testing in the inpatient and outpatient setting is common. Diagnoses precipitating testing are most often non-rheumatic conditions. A positive ANA result changed the clinical diagnosis in a small percentage of patients and rarely informed treatment. <h3>REFERENCES:</h3> <b>NIL.</b> <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> David Karp Support to university from UCB, Eli Lilly, Genentech, Bristol-Myers Squibb, Novartis, and Biogen., Bonnie Bermas: None declared, Shivani Kottur: None declared.