gms | German Medical Science

Introduction: HLA-B27 is strongly associated with ankylosing spondylitis and other forms of spondyloarthritis (SpA). HLA-B27 is included in the ASAS classification criteria for axial and peripheral SpA. HLA-B27 testing has further been advocated as a screening test for axial SpA in patients with chronic back pain. The goal of this study was to analyze the use of the HLA-B27 test in clinical practice.

Methods: We queried the electronic medical records of a large academic hospital network for adults tested for HLA-B27 from 1/1/2022 to 12/31/2022. We examined patient demographics, ordering physician specialty, and concurrent testing for antinuclear antibody (ANA), rheumatoid factor (RF), and anti-cyclic citrullinated peptide (ACCP). Missing data were retrieved by chart review.

Results: A total of 1,977 HLA-B27 tests were ordered for 1,960 patients, 15 patients were tested more than once. Of the patients tested for HLA-B27, 1,223/1,960 (62.4%) were female, the mean testing age was 47.4 years. The age group with the most HLA-B27 tests was 46–55 years in females and 36–45 years in males. HLA-B27 tests were ordered by 426 providers. Rheumatology providers ordered the most HLA-B27 tests (766/1,977, 38.7%) followed by ophthalmology (422/1,977, 21.3%), and oral & maxillofacial surgery (241/1,977, 12.3%). Physical medicine & rehabilitation and orthopedic surgery accounted for only 84/1,977 (4.2%) and 41/1,977 (2.1%) of tests, respectively. 215/1,960 (11.0%) patients tested HLA-B27 positive. The rate of HLA-B27 positivity was 15.6% in ophthalmology, 12.2% in rheumatology and less than 10% in other specialties. Of all HLA-B27 tests, 8.6% were ordered in combination with ANA, 26.2% in combination with RF/ACCP, and 35.6% in combination with both ANA and RF/ACCP. Co-ordering HLA-B27, ANA, RF and ACCP was observed across all specialties, although with varying ratios.

Conclusion: HLA-B27 was ordered by a large spectrum of health care providers, most commonly by rheumatology and ophthalmology, but rarely by physical medicine & rehabilitation and orthopedic surgery, specialties expected to see many patients with back pain. HLA-B27 was ordered for patients across all ages and often in combination with ANA and RF/ACCP, suggesting that it is commonly used as part of a diagnostic panel in patients with peripheral musculoskeletal complaints.