Missed Diagnoses in SpA, Undertreated Patients

February 5, 2019

Half of patients with axial spondyloarthritis have both the axial and peripheral forms of the disease, which may explain why these patients have higher disease activity, researchers write in RMD Open.

Half of patients with axial spondyloarthritis (SpA) have both the axial and peripheral forms of the disease, which may explain why these patients tend to have higher disease activity, researchers write in RMD Open.

The study, by de Winter JJ et al. and colleagues of the University of Amsterdam, was published in the January 11 issue of the journal.

SpA can manifest as axial, peripheral and extra-articular affecting the skin, gut and eye. Prior to the study, it was known that at least 30 percent of patients with SpA have both axial and peripheral disease, such as arthritis, enthesitis and dactylitis, but this study shows that it affects more than 50 percent of patients.

“The data suggest that it remains crucial to assess the overal disease activity and the different domains of the disease-even when classified as axial disease. Treating accordingly may improve outcomes,” the authors wrote.

This was a cross-sectional observational study that included 314 adult patients with SpA who were treated at an outpatient clinic from June 2007 to August 2012 and again from January 2011 to 2012. Of these patients, 230 met the criteria for axial with 51 percent of patients in this group exhibiting both axial disease (demonstrated as back pain) and peripheral disease (such as (arthritis, enthesitis and dactylitis). This group of patients had higher disease activity as compared to patients with only axial disease or peripheral disease.

All of the patients met the criteria for SpA as determined by the Assessment of SpondyloArthritis international Society (ASAS). HLA-B27 status was considered and X-rays of sacroiliac joints were reviewed. Disease activity measures were conducted using the Bath Ankylosing Spondylitis Disease Activity (BASDAI) and Ankylosing Spondylitis Disease Activity Score (ASDAS). Other factors that were considered included a history or presence of psoriasis, uveitis and inflammatory bowel disease.

The study's findings raise a few questions, such as whether these patients are being under treated. Most of the axial SpA patients were treated with NSAIDs and most of the peripheral SpA patients were treated with csDMARDs.

Other findings:
• 21 percent of patients with peripheral SpA had a history of back pain. A diagnosis of axial SpA, requires that back pain be present. 
• Despite the use of csDMARDs, patients diagnosed with both axial and peripheral SpA had significantly higher disease activity. These patients also used less csDMARDs.
• High disease activity in combined SpA did not necessarily indicate the use of TNFi treatments.
• Despite the presence of disease activity, physicians did not employ “treat-to-target.”

“The key question is if merely changing the criteria would impact recognition and treatment of peripheral disease in clinical practice. It may be more relevant to maintain the current classification but clarify in management and treatment guidelines how this should be applied. Careful evaluation and monitoring of peripheral disease (and similarly: extra-articular manifestations and comorbidities) remains needed in all patients with SpA, even in the axial SpA subset. And, treatment decisions should be based on axial disease targets and/or peripheral disease targets and also should include composite indices and/or patient reported outcomes (PROs) reflecting the global disease activity where appropriate,” the authors wrote.



Janneke J de Winter, Jacqueline E Paramarta, Henriëtte M de Jong, et al. “Peripheral disease contributes significantly to the level of disease activity in axial spondyloarthritis,” RMD Open. Jan. 11, 2019. DOI: 10.1136/rmdopen-2018-000802. eCollection 2019.