Prevalence, characteristics, and screening of spondyloarthritis in Japanese patients with early inflammatory bowel diseases: a prospective multidisciplinary study.

Background: The prevalence and characteristics of inflammatory bowel disease-associated spondyloarthritis (IBD-SpA) in Japan are unclear. Moreover, methods for screening SpA among IBD patients have not been established.

Methods: This single-center prospective multidisciplinary study included consecutive patients with IBD, which was newly diagnosed within the past 3 years (early IBD). Board-certified rheumatologists examined the patients for disease history and musculoskeletal manifestations, with imaging studies if needed. Questionnaires assessed patient-reported outcomes and Psoriatic Arthritis Screening and Evaluation (PASE) scores.

Results: We identified 85 eligible patients with early IBD, 22 (25.9%) of whom had Crohn's disease, 63 (74.1%) had ulcerative colitis, and 3 (3.5%) had IBD-SpA diagnosed prior to study enrollment. Rheumatologist evaluations identified additional seven SpA cases, resulting in a total of 10 patients (11.8%) with IBD-SpA (1: axial, 9: peripheral). IBD patients without SpA often presented with back pain (52%) and peripheral joint pain (24%), whereas arthritis, cervical and thoracic pain, and inflammatory back pain were more frequent in IBD-SpA. Newly identified IBD-SpA cases tended to have lower-limb arthritis, dactylitis, and enthesitis, compared with previously diagnosed IBD-SpA cases. For patients with active SpA symptoms in the past 6 months, PASE demonstrated that the area under the receiver operating characteristic curve was 0.87 (95% confidence interval: 0.68, 1.00). The optimal cut-off (33 points) had a sensitivity of 0.88 and specificity of 0.88.

Conclusions: This prospective study found rheumatologist evaluation increased SpA diagnosis and 11.8% of Japanese early IBD patients had IBD-SpA. PASE questionnaires may be effective for screening SpA among IBD patients.