NrxSpA Classification Holds Little Relevance in Daily Practice

While the terms nonradiographic axial spondyloarthritis (NrxSpA) and radiographic axial spondyloarthritis (R-axSpA) may sometimes be helpful for stratifying patients with axial spondyloarthritis (axSpA) in clinical studies, the terms are less relevant in actual clinical practice, according to a review article published in Joint Bone Spine.

Part of the axSpA spectrum, NraxSpA is used to classify patients without definite radiographic sacroiliitis, explained review author Denis Poddubnyy, MD, of the rheumatology department at Charité–Universitätsmedizin Berlin in Germany.

However, the detection of radiographic sacroiliitis via conventional radiography is unreliable and fails to consider new bone formation in the spine, which sometimes occurs early in the disease course, according to the article. Furthermore, other conditions that manifest with bony damage, such as rheumatoid arthritis and psoriatic arthritis, are not defined by “nonradiographic” and “radiographic” stages, so why continue the differentiation with axSpA?

“Importantly, despite some differences … the disease burden (as reflected by the level of symptoms such as pain, stiffness, functional limitations, health-related quality of life) as well as disease course over time are largely comparable between nr- and r-axSpA,” Dr Poddubnyy wrote, “confirming the concept of axSpA as one disease.”

Diagnosing axSpA in daily practice requires a thoughtful estimation of disease probability based on both positive and negative diagnostic test results, including imaging.

“The correct diagnosis is the best predictor of a good treatment response in axSpA that is equally probable at the nr- and r-axSpA given comparable level of inflammatory activity,” Dr Poddubnyy wrote.

Reference

Poddubnyy D. Challenges in non-radiographic axial spondyloarthritis. Joint Bone Spine. 2023;90(1):105468. doi:10.1016/j.jbspin.2022.105468