Clinical phenotypes and therapeutic outcomes in enteropathic arthritis: a multivariate analysis from a retrospective cohort

Objectives: Enteropathic arthritis (SpA-IBD) refers to the coexistence of spondyloarthritis (SpA) and inflammatory bowel diseases (IBD). Whether the initial disease manifestation (SpA-first vs. IBD-first) influences clinical phenotypes and treatment outcomes remains uncertain. This study aimed to evaluate potential associations between disease onset and specific musculoskeletal manifestations, as well as to identify predictors of therapeutic multi-failure. Methods: We conducted a retrospective analysis of patients with SpA-IBD evaluated by both rheumatologists and gastroenterologists at our multidisciplinary ImmunoCenter from March 2022 to March 2024. We compared demographic, clinical, laboratory, and therapeutic characteristics of patients with SpA-first vs. IBD-first presentation. Multivariate logistic regression models were employed to assess associations between disease onset and clinical manifestations, and to identify predictors of therapeutic multi-failure. Results: Sixty-six patients were included (IBD-first: n=47, 71%; SpA-first: n=19, 29%). Enthesitis was more prevalent in the IBD-first group both at SpA onset (38% vs. 10%, p=0.021) and during follow-up (53% vs. 25%, p=0.034). No significant differences were observed in the frequency of axial (65% vs. 64%) and peripheral (60% vs. 66%) involvement or in laboratory parameters between the two groups. In the multivariate logistic regression, IBD-first presentation was significantly associated with a higher likelihood of developing enthesitis after adjusting for confounders (OR=0.267, 95% CI=0.076-0.942, p=0.040). Regarding treatment outcomes, psoriasis was significantly associated with increased risk of therapeutic multi-failure (OR=6.39, 95% CI=1.60-25.47, p=0.009), whereas other phenotypic features were not significantly predictive. Conclusions: The significantly higher likelihood of developing enthesitis in IBD-first suggests that distinct disease onset patterns and clinical phenotypes may influence musculoskeletal manifestations and treatment responses in enteropathic arthritis.