Background/Purpose: Human leukocyte antigens (HLAs) are proteins encoded for by the major histocompatibility complex located on the short arm of chromosome six. One such allele, HLA-B27 is known to have a strong association with ankylosing spondylitis (AS) and is present in over 90% of Caucasian AS patients. The National Capital Consortium’s (NCC) HLA-B27 testing is conducted as a polymerase chain reaction (PCR), sequence-specific oligonucleotide probe analysis. As this is a genetic test, repeating the assay multiple times for the same individual patient is of limited diagnostic utility. The intent of this project was to determine the number of repeat HLA-B27 tests that occur within the NCC during a calendar year and the approximate cost associated with this repeat testing.

Methods: A record of all HLA-B27 tests ordered in the NCC between January 1 2019 and December 31 2019 was obtained. Chart reviews were performed to identify whether these patients had prior HLA-B27 testing conducted over the lifetime of the patient in the electronic medical record (EMR) and the number of prior tests. Ordering location of the testing (primary care, ophthalmology/optometry, rheumatology, other specialty clinic, inpatient, and outside provider) was also recorded. The cost of repeat testing was then estimated per the facility’s contract with LabCorp.

Results: Between January 1 2019 and December 31 2019, 460 HLA-B27 tests were conducted for patients within the NCC. Of these, 33 (7%) represented repeat tests associated with a cost of approximately 5,610 dollars. Five of the thirty-two HLA-B27 tests ordered by outside providers (16%) represented repeat studies associated with a cost of approximately 850 dollars. The specialty with the second highest percentage of repeat tests was ophthalmology and optometry (8 repeat tests, 13% of all tests ordered by the specialty, $1,360 spent in repeat tests), followed by pediatric rheumatology (5, 11%, $850), other specialty clinics (6, 5%, $1,020), primary care (7, 5%, $1,190), and adult rheumatology (2, 5%, $340).

Conclusion: In this review of ordering practices, repeat HLA-B27 testing accounted for 7% of tests ordered in the NCC over one calendar year. While the majority of HLA-B27 tests were ordered in the primary care setting, the highest rates of repeat testing were conducted by outside providers, ophthalmology/optometry, and pediatric rheumatology. This repeat testing is not insignificant; when extrapolated it represents an estimated ten year cost of over $56,000 to our facility. We hypothesize that lack of access to our facility’s EMR, use of order sets, and insufficient time to review the EMR represent major factors contributing to repeat HLA-B27 testing. Our findings suggest that efforts to reduce HLA-B27’s inclusion in order sets and introduction of EMR “flags” to prevent repeat ordering may reflect reasonable interventions to lower repeat testing within our system.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/frequency-and-cost-of-repeat-hla-b27-testing-within-the-national-capital-consortium-over-a-calendar-year/