Psoriasis is an independent risk factor for entheseal damage, not spinal damage, in patients with axial spondyloarthritis (axSpA), as per study results published in Seminars in Arthritis and Rheumatism. Instead, spinal damage was predicted by peripheral enthesitis independent of axSpA subtype.

Investigators prospectively collected data from 120 patients with axSpA in Ottawa, Canada. Demographic information and patient- and clinician-reported outcomes were extracted, including patient age, sex, body mass index (BMI), disease duration, and tender/swollen joint counts. Spine radiographs were evaluated for spinal damage, using the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS). Patients also underwent ultrasound of 12 entheses in the upper and lower extremities to capture entheseal damage and inflammation. Multivariate analyses were performed to characterize the relationship among mSASSS, enthesitis scores, and extra-articular manifestations, including psoriasis.

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Among 120 patients, 114 (95.0%) had axSpA, according to the Assessment of SpondyloArthritis international Society criteria, and 31 (25.8%) had psoriasis. A total of 62 patients were classified as having ankylosing spondylitis (AS), as per the modified New York criteria. Disease characteristics were comparable between patient groups, although patients with psoriatic arthritis (PsA) had more frequent enthesitis than patients with AS (P =.027). Patients with PsA were also less often human leukocyte antigen B27 (HLA-B27)-positive compared with other axSpA groups. In the multivariate model corrected for HLA-B27, psoriasis was an independent risk factor for increased entheseal damage (P =.009), but not entheseal inflammation (P >.05). In addition, BMI (P <.001), age (P =.007), male sex (P =.032), and mSASSS (P =.035) affected entheseal damage, and BMI (P <.001) and male sex (P =.022) predicted entheseal inflammation. Independent predictors of spinal damage included entheseal damage (P =.025), longer disease duration (P =.045), and male sex (P =.041). After adjustments for HLA-B27 positivity, however, entheseal damage emerged as the only predictor of spinal damage (P =.023).

These data suggest that although psoriasis may predict entheseal damage in axSpA, it had no confirmed association with radiographic spinal damage. Instead, peripheral enthesitis was an independent predictor of spinal damage, regardless of SpA subtype. Additional research is necessary to elucidate the pathological mechanisms that underlie each SpA subtype.

Disclosure: One study author declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of the author’s disclosures.

Reference

Solmaz D, Bakirci S, Jibri Z, Sampaio M, Karsh J, Aydin SZ. Psoriasis is an independent risk factor for entheseal damage in axial spondyloarthritis [published online June 28, 2019]. Semin Arthritis Rheum. doi:10.1016/j.semarthrit.2019.06.016