Current Issues in nr-axSpA Diagnostics

Sergio Schwartzman, MD: Non-radiographic axial spondyloarthritis is a relatively new term. It was first coined as part of the classification criteria for spondyloarthritis in 2009. And that completely reorganized the way that we look at spinal arthritis. So, the first division is separating it out into peripheral spondyloarthritis and axial spondyloarthritis. And since we're only traveling down the side of the axial spondyloarthritis component, non-radiographic axial spondyloarthritis refers to a phenotype of patients who have axial spondyloarthritis, but who have not had any changes on X-rays.

And those patients can be categorized via 1 of 2 pathways: patients who have MRI changes, have had back pain for greater than 3 months and the onset of pain before the age of 45, or patients who are HLA-B27 positive, with the same back pain categorization in terms of the classification criteria, but with more features of spinal arthritis in general.

I think the challenges about non-radiographic axial spondyloarthritis are the first is that it is not a diagnosis. It's a classification criteria. A diagnosis is made at the discretion of the physician who's evaluating the patient.

So, the term itself is not meant as necessarily a diagnostic, but more to categorize patients in a uniform manner, so that they can be included in clinical trials. But this concept, though, has evolved to helping rheumatologists identify patients with this group of diseases much earlier than what we had done before. So the first challenge, then, is in understanding what non-radiographic axial spondyloarthritis is. And the way to think about this is that it is part of the entire spectrum of axial spondyloarthritis. It has very similar presentation manifestations, and co-manifestations and comorbidities. It differs in that it may identify patients much earlier than what we see in patients with radiographic disease. And one needs to understand that the disease burden for non-radiographic axial spondyloarthritis is the same as it is for radiographic axial spondyloarthritis or ankylosing spondylitis.

I think rheumatologists need to be educated—and that's the challenging perspective, as to the fact that this entity exists that is characterized by very similar symptoms and what we see ankylosing spondylitis, but it probably represents an earlier part of the disease process, in terms of how it evolves over time.

I think the first challenge is to recognize that these are classification and not diagnostic criteria. The second challenge is to understand that this falls within the spectrum of really one disease process. And I think the third challenge is to think of this as such, but in a manner that necessitates taking a very aggressive approach to treatment, because the disease burden is equal to what we see in ankylosing spondylitis or radiographic axial spondyloarthritis.

There are some subtle differences. Non-radiographic disease is equally present in men and women, whereas ankylosing spondylitis is more common—2:1—in men than it is in women. And the disease may present a little bit differently, more like a fibromyalgia pattern or cervical disease, and not necessarily a lower back pain. So I think that the subtle differences are also important differentiations.