How Best to Assess Axial Involvement in Psoriatic Arthritis?

Aug 28, 2018

Be cautious about relying heavily on inflammatory back pain criteria that were developed for ankylosing spondylitis.

Reference1. Yap KS, Ye JY, Li S, Gladman DD, Chandran V. Back pain in psoriatic arthritis: defining prevalence, characteristics and performance of inflammatory back pain criteria in psoriatic arthritis. Ann Rheum Dis. 2018 Aug 4. pii: annrheumdis-2018-213334. doi: 10.1136/annrheumdis-2018-213334. [Epub ahead of print]

Yap and colleagues at the University of Toronto in Ontario, Canada, found that rheumatologists’ assessments of inflammatory back pain based on criteria developed for ankylosing spondylitis don’t correlate well with radiographic axial involvement in psoriatic arthritis.¹ Scroll through the slides for the details of their study and the take-home points for physicians.

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axPsA, axial psoriatic arthritis.

BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Functional Index; BASMI, Bath Ankylosing Spondylitis Metrology Index.

BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Functional Index; IBP, inflammatory back pain.

Because sensitivity was low, many cases of axial involvement were missed by rheumatologist judgment alone.

AS, ankylosing spondylitis; IBP, inflammatory back pain; PsA, psoriatic arthritis.

There is a very good agreement between the IBP criteria and rheumatologist-judged IBP in PsA, but the positive likelihood ratio of IBP (either by rheumatologist judgment or by IBP criteria) for axial PsA is quite low. Physicians should strive to identify patients with axial disease, since the natural history may differ between patients.