Atul Deodhar MD - Rheumatology Advisor

Atul Deodhar, MD, MRCP

Expert Perspectives

 

Expert Perspectives on Non-Radiographic Axial Spondyloarthritis

Atul Deodhar, MD, MRCP

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Practice Community
Oregon Health & Science University
Hospital and Institutional Affiliations
Professor of Medicine
Medical Director, Rheumatology Clinics, Oregon Health & Science
University

 

Question

What are the limitations of the Assessment of SpondyloArthritis international Society (ASAS) classification criteria for describing nonradiographic axial spondyloarthritis (nr-axSpA)?

Answer

The first thing I want to say is that the ASAS classification criteria should not be used for diagnosis of SpA, which is a big mistake. Erroneous use of the classification criteria for diagnosis can cause more harm, in fact, as people who do not have SpA may be considered to have it.

Let’s get back to how nr-axSpA should be diagnosed. Diagnosis is a process in which you consider the pretest probability of SpA in the patient you are looking at in addition to the fulfillment of certain clinical parameters. These are the same clinical features that are used in the classification criteria; however, if a clinician only uses the classification criteria to establish the diagnosis, they are not taking into account what the pretest probability of SpA is.

The next difference between diagnostic and classification criteria is that classification criteria are “yes” or “no.” A patient either fulfills the criteria or they don’t. Diagnosis is much more nuanced and sensitive, while classification criteria are much more specific, and we don’t want to miss people who might have a condition.

My message is: Don’t use ASAS classification criteria for diagnosis. It is only to be used for classification for clinical trials and research studies. It has no value in day-to-day practice. Instead, I recommend just describing the disease as axSpA. The differentiation between nr-axSpA and ankylosing spondylitis (AS) is completely arbitrary and depends only upon the degree of sacroiliitis present. What we have found is that the degree of sacroiliitis a patient has doesn’t really change their functional status. It may not change their disease burden. The functional capacity loss can be the same in both AS and nr-axSpA. The treatment is the same. The only reason they are differentiated is because pharmaceutical companies had never done clinical trials on nr-axSpA as defined previously, and they needed to show their agents worked in earlier stages of the disease before the patients have definite sacroiliitis.

Question

Imaging remains an important tool for the diagnosis of axSpA, but the role of imaging for monitoring disease activity is less well‐defined. Can you comment on the utility of spine and/or pelvis MRI for patients in whom the degree of active inflammation is unknown?

Answer

Magnetic resonance imaging (MRI) is an important tool because of its sensitivity. The current ASAS definition for diagnosis of axSpA is based on MRI findings on consecutive slices. That is objective, but it is not specific because you see the same thing in patients with mechanical pain, in patients with no backache and no pathology, and in patients who are athletes. So should we be doing routine MRIs in clinical practice to monitor disease activity? The answer is no. You diagnose a patient and then you treat him or her and there are specific indications for doing a repeat MRI. This is more clearly defined in the 2019 update by the American College of Rheumatology, Spondylitis Association of America, and the Spondyloarthritis Research and Treatment Network update of the treatment guidelines for axSpA.

We do not advise using MRI just to see how the patient is doing, as this can be done with clinical measures such as looking at their enthesitis and spinal mobility. MRIs are expensive and should not be used for daily monitoring. Checking C-reactive protein levels is a cheaper way of determining patient disease activity, but C-reactive protein is high only in approximately 30% to 40% of patients, so it may not tell you the entire story.

You can turn to MRI if you have confirmed that your patient is adherent to treatment but is not responding to it.

Question

The Ankylosing Spondylitis Disease Activity Score (ASDAS) has been used to assess disease activity in nr-axSpA. Can you discuss the limitations of ASDAS when applied to nr-axSpA?

Answer

Although Routine Assessment of Patient Index Data 3 (RAPID3) was developed for rheumatoid arthritis, our team wanted to see whether it could be used in axSpA. My fellow led a cross-sectional longitudinal study evaluating the correlation between RAPID3 and the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI). We found that RAPID3 does reliably measure disease activity in axSpA and that it correlates well with BASDAI for monitoring axSpA.

The Ankylosing Spondylitis Disease Activity Score (ASDAS) is even better than BASDAI for measuring disease activity. However, it is not ideal in clinical practice where a rheumatologist may only have 10 or 15 minutes with each patient. So BASDAI or RAPID3 may be good enough to assess axSpA. When combined with ongoing clinical assessment, you can get a good idea of disease activity.

Question

Skeletal disease in axSpA can be accompanied by extra- articular disease including uveitis, psoriasis, and inflammatory bowel disease. Can you discuss changes in treatment regimens when these specific comorbidities arise?

Answer

If a patient has inflammatory bowel disease (IBD) as a predominant problem, we would be hesitant to use interleukin (IL)-17 inhibitors, such as ixekizumab or secukinumab, especially if they have active IBD. Clinical trials evaluating ixekizumab and secukinumab included patients with a history of IBD but not patients with active IBD. So in general, if a patient has a history of IBD but no active disease, IL-17 inhibitors are an option. But if they have active IBD, that treatment option is out.

As for patients with uveitis, monoclonal anti-tumor necrosis factor antibodies are useful and will provide an answer. This is also specifically addressed in the updated axSpA treatment guidelines.

Patients who develop extra-articular disease after being on a biologic agent for axSpA have clearly not responded to the treatment. You can either change the initial biologic immediately depending on comorbidities or elect to treat just the uveitis, for example, with prednisone ophthalmic drops if you believe this is a one-off situation. Since there are limited options for treating axSpA to start with, you don’t want to throw out the drug just because a patient has 1 episode of an extra-articular manifestation.

Question

What are the current knowledge gaps in axSpa, including education gaps in diagnosis and treatment?

Answer

There are many education gaps, beginning with people making wrong diagnoses by ticking boxes using disease classification criteria, which should never happen. There is a lot of education needed as to what axSpA is and how it should be diagnosed. The education gap among primary care physicianss, chiropractors, osteopathic clinicians, spine surgeons, and neurosurgeons is huge. These are the healthcare professionals who are often the first to see patients with initial back pain. For example, patients with axSpA may have incidental bulging discs between L3 and L4 and see a neurosurgeon for surgery, but after the surgery the backache continues since the axSpA was not diagnosed. What needs to happen is the education of both physicians and patients alike. Organizations like the Spondylitis Association of America should be providing part of that education to patients and the general public.

From the point of view of axSpA treatment, we still do not have prospective studies that definitively show that drugs prevent osteoproliferation. We believe that the biologics do that, but our experience is via retrospective analysis. Establishing a cause-and-effect relationship requires prospective studies, and those are lacking.

The third knowledge gap is that patients with axSpA commonly complain of pain and fatigue. Patients are not concerned about osteoproliferation. Their main concern is that their back hurts and they are extremely fatigued. As rheumatologists, we have found ways to control the inflammation but not always to address the fatigue. We need to find out what the other pain pathways are that are activated in this inflammatory condition. This lack of understanding of the pain and fatigue in axSpA is a big gap in our knowledge.