Overview of Non-Radiographic Axial Spondyloarthritis

Transcript: Sergio Schwartzman, MD: Hello and welcome to this HCPLive® Peer Exchange, “Understanding Non-Radiographic Axial Spondyloarthritis.” I am Dr Sergio Schwartzman, a rheumatologist from Weill Cornell Medical College and the Hospital for Special Surgery. Joining me today in this virtual discussion are 2 of my rheumatology colleagues—Dr Atul Deodhar from the Oregon Health & Science University, and Dr Philip Mease from the Swedish Medical Center—and Ms Tiffany Westrich-Robertson, who's with the International Foundation for Autoimmune & Autoinflammatory Arthritis and actually has axial spondyloarthritis.

Today we are going to discuss a number of topics pertaining to the diagnosis and management of non-radiographic axial spondyloarthritis. Let’s get started with our first topic.

The first question is, what is non-radiographic axial spondyloarthritis? I will take this first question. The term non-radiographic axial spondyloarthritis is relatively new to us. It was actually developed and coined in 2009 by ASAS [Assessment of Spondyloarthritis International Society] with the intent being to identify patients who have axial spondyloarthritis early, and also as classification criteria to create a group of patients who are homogeneous, particularly for clinical trials.

In terms of the actual definitions of radiographic and non-radiographic axial spondyloarthritis, I am going to ask Dr. Atul Deodhar to speak to that.

Atul Deodhar, MD, MRCP: Thank you, Sergio. I would take a step back and say that spondyloarthritis is a family of diseases in rheumatology, as you know. Although, for all of the rheumatic diseases that we see in daily clinical practice, we try to group them to families with similar clinical manifestations, similar genetic backgrounds, and so forth. Spondyloarthritis is a family of rheumatic diseases that have typical clinical features, a typical clinical phenotype.

There is spinal involvement; there is peripheral involvement, synovitis, and enthesitis. The spondyloarthritis family also has involvement of the skin in the form of psoriasis, eye involvement in the form of uveitis, and so forth. Genetically, these diseases have HLA-B27 [human leukocyte antigen B27] as a common genetic background. Under the family of spondyloarthritis, we can divide that family into axial versus peripheral spondyloarthritis. Peripheral spondyloarthritis would have psoriatic arthritis and arthritis with inflammatory bowel disease.

Axial spondyloarthritis is divided into radiographic and non-radiographic axial spondyloarthritis. Radiographic spondyloarthritis is when we have definitive changes of sacroiliitis on the plain x-ray of the sacroiliac joint, and non-radiographic is if the changes of sacroiliitis are not that definitive. The ankylosing spondylitis that all of us have known for a very long time is radiographic axial spondyloarthritis, where the changes of sacroiliitis are definitive on the plain x-ray of the sacroiliac joint.

Non-radiographic axial spondyloarthritis is still part of axial spondyloarthritis, but the changes of the sacroiliitis on plain X-ray are not obvious or perhaps totally absent. That's the only difference between radiographic and non-radiographic. It's the degree of sacroiliac joint involvement on plain x-ray.

Sergio Schwartzman, MD: Thank you. Do you think that this is indeed an important differentiation with regard to the natural history of the disease or with therapies? We'll get to therapies in detail soon.

Atul Deodhar, MD, MRCP: That's a very important question. As you rightly said initially, the 2009 classification criteria by the ASAS group coined these terms, and that was mainly done for clinical trials to get the homogeneous patients into a trial. In day-to-day practice, these terms should not matter because as we will discuss later, the clinical presentation, the burden of the disease, the treatments, and the outcomes can be quite similar.

Of course, if you take the extreme ankylosing spondylitis where someone has bamboo spine, that would have a very different outcome. One can say that these are the 2 extremes of the same spectrum of the disease. So in day-to-day practice, it shouldn't matter whether it is non-radiographic or radiographic, as long as you are able to diagnose axial spondyloarthritis and treat those patients. That is the most important part of understanding this spectrum.

Sergio Schwartzman, MD: Atul, one of the huge advantages of this classification criteria is that it has sensitized the rheumatology community to identify this disease group a lot earlier, which was probably not the case before 2009.

Atul Deodhar, MD, MRCP: That is a great point, and you're absolutely correct. When I was a fellow in rheumatology, we were taught about ankylosing spondylitis, and these patients have backache. What we didn't understand was how these patients existed before they developed classic sacroiliitis. We had no way of diagnosing these patients early. We still recognize some of these patients and say they have undifferentiated spondyloarthritis, incomplete ankylosing spondylitis, and so forth, but you're absolutely right.

Now we have the advent of MRI [magnetic resonance imaging], which actually revolutionized this space of medicine, and now we are able to appropriately use the MRI in making the diagnosis of this condition before x-ray changes. Because of this 2009 classification criteria, it led the pharmaceutical industry to do more clinical trials. Rheumatologists are sensitized and are understanding this more. They are trying to find these patients early and treat them.

Sergio Schwartzman, MD: Thank you.

Transcript Edited for Clarity