PO:01:008 | Active sacroiliitis at magnetic resonance enterography increases the risk of axial spondyloarthritis in Crohn’s disease patients, while greater age and disease duration are protective factors: a monocentric retrospective cohort study

Gabriele Amati¹, Gilda Sandri^1|2, Giovanni Ciancio², Benedetta Bongiovanni^1|2, Martina Orlandi^1|2, Ottavio Secchi^1|2, Davide Vaccari³, Annarita Pecchi⁴, Angela Bertani⁵, Maddalena Pecchini⁵, Pietro Torricelli⁴, Antonio Colecchia⁵, Dilia Giuggioli^1|2. | ¹Struttura Complessa di Reumatologia, Azienda Ospedaliero-Universitaria Policlinico di Modena, Modena, Italy; ²Cattedra di Reumatologia, Università degli studi di Modena e Reggio Emilia, Modena, Italy; ³Unità Operativa di Radiologia, Ospedale di Pavullo, AUSL di Modena, Modena, Italy; ⁴Struttura Complessa di Radiologia, Azienda Ospedaliero-Universitaria Policlinico di Modena, Modena, Italy; ⁵Struttura Complessa di Gastroenterologia, Azienda Ospedaliero-Universitaria Policlinico di Modena, Modena, Italy.

We aim to estimate the incidence of IBD-SpA in a population of Crohn’s disease (CD) patients and to identify risk factors associated with the development of IBD-SpA. This retrospective observational cohort study included all consecutive patients with a CD diagnosis followed by our IBD outpatient clinic who underwent at least one magnetic resonance enterography (MRE) between 2011 and 2023. Patients without a full scan of sacroiliac joints (SIJs) on MRE, having other rheumatic diseases, diagnosed with SpA before CD diagnosis, missing key clinical or imaging data, death or lost to follow-up at the time of data collection, were excluded. The identification of new onset IBD-SpA during the follow-up was based on the fulfillment of the ASAS classification criteria. Baseline demographic and clinical data, and immunosuppressive therapies performed were collected. Presence of articular and intestinal lesions at MRE was established according to the most recent definitions by ASAS and the Society of Abdominal Radiology, respectively. Incidence rates were calculated as the number of new cases of SpA divided by the total person-time at risk, expressed per 1,000 person-years. Log-rank test and univariate Cox proportional hazards regression analyses were performed to estimate hazard ratios (HR) for categorical and continuous predictors. A total of 147 CD patients [M:F 1:1, median age (IQR) 46.3 (23.3) years, median CD duration (IQR) was of 4.50 (16.4) years] were selected. Descriptive statistics of the sample are shown in Table 1. The incidence rates of overall, axial, and peripheral IBD-SpA were 3.8, 2.1, and 1.7 cases per 1,000 person-year, respectively. A stricturing CD behavior (HR: 0.22; 95% CI: 0.05–0.93; p=0.040), baseline mesalazine treatment (HR: 0.24; 95% CI: 0.06–0.99; p=0.049), greater age (HR: 0.94; 95% CI: 0.89–1.00; p=0.035), and CD duration (HR: 0.84; 95% CI: 0.72–0.97; p=0.019), were associated with a reduced risk of developing IBD-arthritis. The sub-analysis conducted for each subset of arthritis revealed an increased risk of axial IBD-SpA for active sacroiliitis (HR 6.08; 95% CI 1.11-33.4; p=0.038), and ankylosis of SIJs on MRE (HR 47.7; 95% CI 2.99-763.4; p=0.006), while revealed a reduced risk for baseline mesalazine treatment (HR 0.20; 95% CI 0.04-1.11; p=0.067), greater age (HR: 0.93; 95% CI: 0.86–1.00; p=0.040) and CD duration (HR: 0.84; 95% CI: 0.71–0.99; p=0.033). An increased risk of peripheral IBD-SpA emerged only for ankylosis of SIJs (HR 24.6; 95% CI 2.23-271.8; p=0.009). A reduced incidence rate of IBD-SpA was associated with a stricturing CD behavior, baseline mesalazine treatment, increasing age and CD duration. Active sacroiliitis at baseline MRE was associated with the development of axial IBD-SpA; mesalazine therapy, greater age and CD duration were protective factors. Table 1: descriptive statistics of the sample.