Diagnosing axSpA in Patients With Chronic Back Pain

A diagnosis of definite-axial spondyloarthritis ((d-)axSpA) can often be reliably made in about 1/3 of patients with chronic back pain (CBP) who were referred to the rheumatologist; however, diagnostic uncertainty may persist in about 5%-30% of patients after 2 years, according to a study published in Annals of the Rheumatic Diseases.

Researchers aimed to investigate the prevalence of axial spondyloarthritis (axSpA) in patients with chronic back pain of less than 2 years’ duration referred to a rheumatologist. Additionally, they analyzed the development of diagnosis over time, and patient characteristics of those developing daxSpA over 2 years using the 2-year data from SPondyloArthritis Caught Early, a European cohort of patients (<45 years) with CBP (≥3 months, ≤2y) of unknown origin. The diagnostic workup comprised evaluation of clinical SpA features, acute phase reactants, HLA-B27, radiographs, and MRI (sacroiliac joints and spine), with repeated assessments. During each visit (baseline, 3 months, 1 year and 2 years), rheumatologists reported a diagnosis of axSpA or non-axSpA with level of confidence (LoC; 0-not confident at all to 10-very confident).

Results showed that in 552 patients with CBP, d-axSpA was diagnosed in 175 (32%) at baseline and 165 (30%) at 2 years. Additionally, baseline diagnosis remained rather stable: at 2 years, baseline d-axSpA was revised in 5% of patients with 8% who 'gained' d-axSpA. However, diagnostic uncertainty persisted in 30%. HLA-B27+ and baseline sacroiliitis imaging discriminated best 2y-d-axSpA versus 2y-d-non-axSpA patients with good response to nonsteroidal anti-inflammatory drugs and MRI-sacroiliitis most frequently developed over follow-up in patients with a new d-axSpA diagnosis. Within the patients who developed MRI-sacroiliitis, 7/8 were HLA-B27+ and 5/8 male.

“Repeated assessments yield is modest, but repeating MRI may be worthwhile in male HLA-B27+ patients,” the authors concluded.

Reference
Marques ML, Ramiro S, van Lunteren M, et al. Can rheumatologists unequivocally diagnose axial spondyloarthritis in patients with chronic back pain of less than 2 years duration? Primary outcome of the 2-year SPondyloArthritis Caught Early (SPACE) cohort. Ann Rheum Dis. Published April 11, 2024. doi:10.1136/ard-2023-224959