Misconceptions in Differentiating Nr-AxSpA and AS

Transcript: Sergio Schwartzman, MD: Phil, is there a lot of misunderstanding in the medical community outside or even inside rheumatology about the differences between non-radiographic axial spondyloarthritis and radiographic axial spondyloarthritis, also known as ankylosing spondylitis? Can you please comment on that and whether there is any approach to addressing that issue if it exists?

Philip J. Mease, MD: There absolutely is a significant misunderstanding, and I'll give you some examples of that in a moment. I'll start with the second question you posed, which is how these terms can be more easily understood. Personally, I think it's looking a decade from now when we're no longer using the term non-radiographic axial SpA [spondyloarthritis] or radiographic axial SpA, but rather we're simply calling the condition axial spondyloarthritis. I'll use rheumatoid arthritis as an analogy. Do you typically say, “Is there a negative rheumatoid arthritis, and is there a positive rheumatoid arthritis,” every time you use the term rheumatoid arthritis? Sergio?

Sergio Schwartzman, MD: The answer is no, but I would probably have phrased that question a little bit differently. I would ask, “Would you use the term erosive rheumatoid arthritis versus nonerosive rheumatoid arthritis?”

Philip J. Mease, MD: Perfect, and the answer to that also is no. I would say that eventually, we're going to come to our senses and we'll call it as it is—axial spondyloarthritis—as if we’re just talking about a large spectrum. One of the things that's very important to understand is that we're using the term spectrum with perhaps the sense that patients with non-radiographic axial SpA will eventually become axial SpA patients, and that non-radiographic is just an earlier, less severe form.

However, that's not correct either because many patients whom we see will remain forever in the group of non-radiographic, especially women. So we do know that when we look at the classic term of ankylosing spondylitis or radiographic axial SpA that patients typically are more frequently male. The current statistic is around 2 to 1 for the male-to-female ratio. It is a fairly high prevalence of HLA-B27 [human leukocyte antigen B27] positivity in that group. When we broaden the classification to include the patients whom we're calling non-radiographic, that's when we're including many more females.

When you put it all together, it's equigender. We don't see much of a difference in the frequency in males versus females in the whole spectrum. There is something about the female gender that is somewhat protective against developing some of the most severe features, the severe ankylosis for example, which is good for women. But what's bad for women is that they end up getting misclassified, and the correct diagnosis is not reached for many years.

In the past, it would be one of the findings that it took almost 10 years for the diagnosis to be made in women, whereas in men it would take only 4 years to 6 years because, as Atul mentioned, we used to think of it as predominantly a male disease. I believe Tiffany will be sharing with us shortly her experience with the trials and travails of coming to a diagnosis. Sergio, you alluded to the point that there are going to be different types of misunderstanding both outside and potentially inside of the rheumatology community of clinicians.

Beginning with outside the community is where a huge amount of education needs to be done. Many family practitioners, orthopedists, physiatrists, and so forth have this old understanding of ankylosing spondylitis. They're used to seeing radiographs that have significant sacroiliac disease on them or syndesmophytes on the spine images. Then they think of it as a male disease. They think of it as being HLA-B27 positive if they check that at all, and they know it is a very severe disease.

If they're old enough, they assume that there's not much that we can do therapeutically, although the advent of the biologics has revolutionized our ability to take care the whole spectrum of disease. So there's a tremendous amount of education that needs to be done for primary care physicians, surgeons, orthopedic surgeons, and so forth to improve at least their suspicion that an inflammatory arthritis in the spine may be occurring and to triage these patients to get to be seen by rheumatologists to complete the work-up.

Also needed is, if HLA-B27 testing hasn't been done, to do so, and to make sure that sacroiliac images are obtained and not just lumbar spine films for evaluating back pain. Part of the problem is that back pain is so common in the population that it's too easy for a family practice clinician to say that what the patient is experiencing is mechanical back pain, degenerative arthritis in the spine, or fibromyalgia, and not to tumble to the possibility that this could be an inflammatory immunologic process that absolutely has something that we can do to treat it.

That's outside the rheumatology community. Within the rheumatology community, there is also a lot of misunderstanding. For example, many people will hear the term non-radiographic and think that includes MRI [magnetic resonance imaging] scanning. The MRI is not a radiographic technique. It's a separate imaging technique. All we’re talking about is that we don't see the type of damage that can accrue over time in someone that would show up on a radiograph.

MRI is much more sensitive to picking up information and structural changes earlier than radiographs will, and so that's important. It's also important to think about the patients who present with clinical features and perhaps not even have MRI changes yet. The clinical features that are suggestive of the spinal arthritis are associated conditions like uveitis, or inflammatory bowel disease, or features of inflammatory back pain that can include the pain getting better with activity and worse with rest—where the patient is awakening in the middle of the night with pain because they have gelled lying there in bed.

There needs to be an improved understanding of being sensitized to how to sort out the possibility of inflammatory back pain and making the diagnosis within the rheumatology community.

Transcript Edited for Clarity