Background/Purpose:   ANA test is a commonly used initial screening for connective tissue diseases (CTD). The ultimate clinical utility of this highly sensitive test depends on the pretest diagnostic probability. It should not be a first line test for the investigation of musculoskeletal symptoms like fatigue or joint pains, unless accompanied by other clinical features to suggest autoimmune disease. It can be positive in multiple autoimmune and mixed connective tissue disorders. It can also be falsely positive in multiple other scenarios. ANA test rarely needs to be repeated. It is a diagnostic, not monitoring test. If an unexpected result is given, it is reasonable to repeat the test to confirm the finding. It is also useful to repeat if a person’s illness has significantly changed. It, however, has no correlation to disease activity in SLE or other CTD. A trend of repeating ANA testing on patients with a history of positive ANA was noted in our outpatient multispecialty clinic. The purpose of this study is to review how frequently patients with known positive ANA testing undergo repeat ANA testing, the reason for it and the specialty and level of training of providers ordering it.

Methods:   Retrospective chart review was performed on 598 patients who underwent ANA testing between April 1^st, 2015 and March 31^st, 2016. Data collected included: Age, gender, positive ANA test result, reason for ordering ANA, specialty and level of training of provider ordering ANA. Patients with a positive ANA were identified first followed by review of number of repeat ANA testing after first positive result. Data analyzed using percentage to determine frequency of events.

Results:   Of the total of 598 patients undergoing ANA testing between April 1^st 2015 and March 31^st 2016, 196 (32.8%) patients had a positive result. All patients were older than 18 years, 140 (71.4%) were females and 56 (28.6%) were males. Repeat ANA was noted in 111 (56.6%) patients. Of those, 58 (52.2%) patients had repeat testing once, 23 (25.5%) twice, 11 (9.9%) three times, 8 (7.2) four times, 2 (1.8%) five times, and 9 (8.1%) six or more times. There were 2 patients who underwent repeat ANA test 33 and 56 times. A total of 194 (64.4%) of 301 providers ordering repeat ANA testing were identified. Rest were not available. Most were rheumatologists 76 (39.1%) and primary care physicians 67 (34.5%). Remaining included gastroenterology, pulmonary, dermatology, nephrology and emergency medicine. Majority of repeat tests wherein data was available (172 total) were ordered by attending physicians 162 (94.1%).

Conclusion:   Further education and emphasis should be given on appropriate ANA testing criteria in order to decrease misuse and increase cost effectiveness.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/repetitive-requisition-of-antinuclear-antibody-testing-ana-in-outpatient-multispecialty-clinics-in-patients-with-a-known-positive-ana/