Antinuclear Antibody Multiplex Utilization Across a Large Federal Hospital System: An Investigation of Ordering Practices and Rheumatologic Outcomes.

OBJECTIVE

To understand the ordering patterns of antinuclear antibody (ANA) multiplex testing in a single, large US Department of Defense (DoD) tertiary healthcare system.

METHODS

Records of patients with an ANA multiplex assay ordered over a 1-year period were evaluated in a large DoD hospital system. Duplicate tests and patients with a previously established autoimmune rheumatic disease (ARD) prior to the year of study were excluded. The remaining 2499 patients' charts were reviewed for clinical presentation, ordering specialty, ordering rationale, and whether subsequent rheumatology evaluations resulted in a new ARD diagnosis.

RESULTS

The ANA multiplex assay was ordered most often by primary care and medicine subspecialties for > 100 reasons. In the ANA multiplex assay-negative group, 37/2228 (1.66%) individuals were diagnosed with a new ARD. In the ANA multiplex assay-positive group 37/271 (13.7%) individuals were diagnosed with a new ARD. Sjögren disease, systemic lupus erythematosus, and undifferentiated connective tissue disease were the most common newly diagnosed ARDs in the ANA multiplex assay-positive group. Rheumatoid arthritis and seronegative spondyloarthritis were the most common new ARD diagnoses in the ANA multiplex assay-negative group. In this study, 97% of the ordered ANA assays did not lead to an ARD diagnosis.

CONCLUSION

This study demonstrates frequent utilization of the ANA multiplex assay in the evaluation of nonspecific signs and symptoms, with a low rate of ANA-associated ARDs suggesting a need for implementation of strategies to improve understanding of appropriate clinical contexts that warrant ANA testing.