Clinicians are often faced with uncertainty regarding the diagnosis and treatment of patients with non-radiogrphic axial spondyloarthritis (SpA), but the Monday Clinical Practice session Axial SpA or No Axial SpA: What To Do When X-Rays Are Negative will help to shed light on these important topics.
Axial spondyloarthritis (SpA) is one of the most prevalent inflammatory diseases in the rheumatology field. The term axial SpA is relatively new and incorporates patients with radiographic and nonradiographic disease.
“Axial SpA describes one disease spectrum with an artificial distinction between patients with radiographic and nonradiographic disease,” said Désirée van der Heijde, MD, PhD, of Leiden University Medical Center, Netherlands. “Classification criteria cannot be used to make a diagnosis, and imaging is an important tool, but only in the right clinical context.”
During her presentation, which will take place from 7:30 – 8:30 am in Room B304-305, Building B in the Georgia World Congress Center, Dr. van der Heijde will discuss axial SpA as a clinical diagnosis. To appropriately diagnose axial SpA, knowledge about the heterogeneous clinical picture is key, she said.
Although chronic back pain starting before age 45 is a central symptom, additional musculoskeletal symptoms and extra-rheumatological manifestations may be present. Most patients will have only a few signs and symptoms and in varying combinations. No tests can confirm the diagnosis.
Dr. van der Heijde will also discuss the appropriate use of imaging.
“Imaging, especially of the SI-joints, is important to diagnose a patient with axial SpA. Both radiographs and MRI can be used,” Dr. van der Heijde said. “Radiographs can only assess structural damage, while MRI can show both inflammatory and structural changes.”
However, correct assessment is challenging, especially of the SI joints on radiographs, she added. Abnormalities on MRI of the SI-joints can also be seen in a high percentage in people without axial SpA. Consequently, abnormalities on imaging should be judged only in the context of the entire clinical picture.
Dr. van der Heijde will also discuss the misuse of Assessment of SpondyloArthritis international Society (ASAS) classification criteria for diagnosis of axial SpA, which frequently results in missing a diagnosis or making an incorrect diagnosis.
“This is particularly if the pretest probability of the diagnosis is low — for example, in a general practice setting or a general back pain clinic — but even in a setting of a relatively high pretest probability of around 30%, a wrong diagnosis is made in about one-third of the patients,” she said. “This cannot be solved by increasing the specificity of classification criteria.”
Dr. van der Heijde will close with a discussion about similarities of disease burden and treatment of patients with nonradiographic and radiographic axial SpA.
There are some differences between the two subsets of the disease. For example, more women are diagnosed with nonradiographic axial SpA, whereas more men are diagnosed with radiographic axial SpA. Levels of inflammation are frequently higher in patients with radiographic axial SpA. However, the other signs and symptoms are very similar, as is the level of disease activity. As a result, treatment of the two and response to treatment is very similar.
“The main difference is the fact that objective signs of inflammation — for example, elevated CRP or inflammation on MRI — should be present before a bDMARD is indicated in patients with nonradiographic axial SpA, but also patients with radiographic axial SpA with objective signs of inflammation respond better to bDMARD therapy,” Dr. van der Heijde said. “Given all the similarities and the difficulties in the correct assessment of radiographic sacroiliitis, it is preferred to use the term axial SpA to diagnose a patient and it is not necessary to make a distinction between nonradiographic and radiographic axial SpA.”