Presentation of Enthesitis Related Arthritis and Juvenile-onset Spondyloarthritis, a Cross-sectional Study in a Pediatric and Adult Clinic

Abstract

Background Juvenile idiopathic arthritis (JIA) comprises a whole spectrum of chronic arthritis starting before 16 years of age. The study aims to explore the clinical and demographic descriptors, treatment, and disease progression of enthesitis-related arthritis (ERA) in comparison with juvenile-onset spondyloarthritis (SpA). Methods Cross-sectional analysis of consecutive patients in two dedicated clinics, with one visit and retrospective case-note review. Arthritis, enthesitis and sacroiliitis were evaluated by scoring disease activity and damage. Continuous variables were reported by median, interquartile range; categorical variables were reported by the frequency comparison of the two groups. Results Thirty-three cases, 23 (69.7%) of ERA, were included. The median age at diagnosis was 12.5 y (SpA) vs. 9 y (ERA) (p < 0.01); the time from symptom onset to diagnosis was 5.5 y (SpA) vs. 1.5 y (ERA) (p < 0.03). In both groups, the predominant presentation was a single joint or < 5 lower limb joints and asymmetric involvement, with a high frequency of enthesitis. There was a higher frequency of mid-tarsal and ankle synovitis in the ERA group and hip involvement in those with SpA. The comparison of the frequency of spine symptoms at presentation, 30% SpA vs. 21.7% ERA (p = 0.7), was not significant, and progression to spinal involvement occurred in 43.5% of ERA patients. The median time for spinal progression was 2.3 and 12 y for ERA and SpA, respectively. Activity and damage scores were not significantly different between the groups. Treatment comparison resulted in 91.3% of ERA and 100% SpA being treated, predominantly with NSAIDs in both groups, followed by DMARDs and biologics, with a higher frequency of biologics in SpA. Conclusion The main differences were that SpA had late diagnoses and hip spine involvement, with a higher frequency of biologic treatment, than ERA.