Characterization of Patients With Axial Spondyloarthritis by Enthesitis Presence: Data from the Corrona Psoriatic Arthritis/Spondyloarthritis Registry

Objective: To compare the characteristics of patients with axial spondyloarthritis (axSpA) who had enthesitis versus those without enthesitis.

Methods: This study included adult patients with axSpA enrolled in the Corrona Psoriatic Arthritis/Spondyloarthritis Registry (March 2013 to August 2018). Enthesitis was assessed at enrollment via the Spondyloarthritis Research Consortium of Canada Enthesitis Index. Characteristics were compared between patients with and without enthesitis using t tests or Wilcoxon rank-sum tests for continuous variables and χ or Fisher exact tests for categorical variables.

Results: Of 477 patients with axSpA, 121 (25.4%) had enthesitis (mean, 3.9 sites) at enrollment. Higher proportions of patients with enthesitis were female and had nonradiographic axSpA than those without enthesitis (both P < 0.05). Additionally, higher proportions of patients with enthesitis had prior biologic (38.8% vs 27.2%) and conventional synthetic disease-modifying antirheumatic drug (csDMARD; 24.8% vs 13.3%) use and were currently receiving a combination of biologics and csDMARDs (28.6% vs 18.1%) than those without enthesitis. Patients with enthesitis had worse disease activity (tender and swollen joint counts, physician global assessment, Ankylosing Spondylitis Disease Activity Score, Bath Ankylosing Spondylitis Disease Activity Index, and Bath Ankylosing Spondylitis Functional Index), spinal mobility, and quality of life (pain, fatigue, Health Assessment Questionnaire, and EuroQol visual analog scale scores); greater work impairment; and had a history of depression and fibromyalgia than those without enthesitis (all P < 0.05).

Conclusion: In this US-based real-world study, enthesitis in patients with axSpA was associated with worse disease activity and quality of life than those with no enthesitis.