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FRI0634 Cost savings of using hla-b*27 tag snp genotyping to determine hla-b*27 status in a canadian population

Background: HLA-B*27 is a useful genetic marker for screening axSpA [1,2] to determine who can benefit from rheumatologic evaluation in a primary care setting [3]. Currently, entire HLA-B locus tests are the gold standard for determining HLA-B*27 status but they are expensive. With a sensitivity of 97.6%, the cheaper HLA-B*27 tag-SNP assay could offer a less expensive yet rigorous testing option. Specifically, the HLA-B*27 tag-SNP assay could be ordered as first-line screening test for patients with inflammatory axial pain by primary care doctors, with the HLA-B locus assay only requested by rheumatologists for patients with a negative tag-SNP test result but a strong clinical suspicion of HLA-B*27 positivity. Economic impact of this hybrid testing strategy is not yet established. Objectives: To determine the cost savings of using the hybrid testing strategy instead of giving HLA-B locus assay to all patients with inflammatory axial pain. Methods: We estimated the total cost of using the HLA-B*27 tagSNP assay for a sample of 510 patients who underwent the test between August 1, 2016 and July 31, 2017 in Newfoundland and Labrador, Canada. We compared this cost with the cost that would have been incurred if these same patients were instead tested with the HLA-B locus test. Results: Total cost of testing 510 patients with HLA-B locus test was $30,557 at an average cost of $60 per test. Cost of testing these patients with HLA-B*27 tagSNP assay was $1,673 (with average cost per test of $3.28). Among those who tested negative on the HLA-B*27 tagSNP assay, 2.3% (~10 patients) would be falsely diagnosed negative. The HLA-B locus test would be ordered in half of these patients after medical history is reviewed by a rheumatologist. Hence, total costs of testing 510 patients with the HLA-B*27 tagSNP assay were $1,963. Consequently, cost savings from using HLA-B*27 tagSNP assay instead of HLA-B locus tests were $28,594 for this sample of 510 patients. This amounted to a 94% reduction in costs relative to the scenario where all patients are tested with HLA-B locus tests. Conclusions: Screening for HLA-B*27 status among axSpA patients of Caucasian decent with HLA-B*27 tag-SNP testing with the gold standard HLA-B locus test only requested for those in whom such need is determined by rheumatologists can result in significant cost savings relative to giving HLA-B locus tests to all patients with inflammatory axial pain. Acknowledgements: 1. Robinson PC, Brown MA. Mol Immunol. 2014;57:2–11. 2. Bennett AN, McGonagle D, O'Connor P, Hensor EM, Sivera F, Coates LC, et al. Arthritis Rheum. 2008;58:3413–8. 3. Sieper J, Srinivasan S, Zamani O, Mielants H, Choquette D, Pavelka K, et al. Ann Rheum Dis. 2013;72:1621–7. 4. Lehr J, Rahman P, O'Rielly DD. J Rheumatol. 2017 Jun;44(6):962–963. Disclosure of Interest: None declared