The role of a multidisciplinary approach in the early and differential diagnosis of inflammatory bowel disease–related spondyloarthritis: insights from a cross-sectional study

Objectives: Inflammatory bowel disease-related spondyloarthritis (IBD-SpA) commonly complicates IBD. Early diagnosis is essential; however, it is often delayed due to clinical heterogeneity and the lack of specific diagnostic criteria. This study aimed to evaluate the outcomes of close collaboration between gastroenterologists and rheumatologists in the classification of the musculoskeletal (MSK) manifestations in IBD patients, focusing on the early diagnosis of IBD-SpA and its differentiation from other conditions. Methods: Consecutive IBD outpatients underwent a comprehensive rheumatologic evaluation during a joint rheumatologist-gastroenterologist consultation, including the DETection of Arthritis in Inflammatory boweL diseases (DETAIL) screening questionnaire, and, when appropriate, laboratory and imaging investigations. Suspected IBD-SpA cases were classified as newly diagnosed IBD-SpA, having an alternative arthropathy diagnosis, or having non-specific arthralgias, and their characteristics were analyzed. Results: A total of 605 IBD patients were evaluated. At the first assessment, 81 patients had a pre-existing diagnosis of SpA and 117 patients of suspected IBD-SpA cases were identified. Among the latter assessment, 18 (15%) were confirmed as new IBD-SpA diagnoses, resulting in a 22% relative increase in the total number of SpA cases and raising the overall prevalence from 13.4 to 16.4%. Patients with axial involvement experienced a longer diagnostic delay (mean 12.4 vs. 2.9 years, p = 0.035). Of the new IBD-SpA diagnoses, 72% resulted in treatment modifications jointly decided by the gastroenterologist and rheumatologist. However, 85% of suspected IBD-SpA cases were ultimately excluded, with 60% classified as other arthropathies (primary osteoarthritis and fibromyalgia) and 25% as non-specific arthralgias. The swollen joint count was the only significant predictor of a new IBD-SpA diagnosis (adjOR 5.70, p < 0.001), with a trend toward significance for fecal calprotectin levels ≥200 μg/g (adjOR 2.88, p = 0.070). Conclusion: The multidisciplinary approach enables early and accurate diagnosis of IBD-SpA, minimizing the risk of misclassification of musculoskeletal manifestations and unwarranted treatment changes.