DOP60 Prevalence of undiagnosed inflammatory Bowel Disease in patients with spondyloarthritis: EISER Study
Authors: Gutiérrez Casbas A , Rodríguez-Lago I , Marín-Jiménez I , Plaza Z , Gratacós J , Trujillo E , Pérez-Pampín E , Barreiro de Acosta M , Aznar-Esquivel A , Carrillo M , García-Vivar M L , Muñoz-Villafranca M D C , Ladehesa L , Iglesias-Flores E , Merino C , González-Lama Y , Arévalo M , Calvet X , Brandy-García A , Izquierdo-Romero M , Manrique S , Olmedo R , García-LLorente J F , Zugaza J , Ros-Vilamajo I , Rull N , Pinto-Tasende J A , Ucha P , González C , Rodríguez-Martín F , Serrano S , Domínguez-Alvaro M , Prado-Galbarro F J , Sanz J 
Published: January 2024

Abstract

Background
A significant proportion of patients with inflammatory bowel disease (IBD) have concomitant rheumatological manifestations. Patients with spondyloarthritis (SpA) often report gastrointestinal symptoms, some of them being associated to IBD. However, the exact prevalence of this disorder is still controversial, and the optimal approach to its diagnosis remains unknown.

Methods
Aim: to determine the prevalence of undiagnosed IBD in patients with axial SpA and psoriatic arthritis (PA). EISER is an observational, cross-sectional study carried out in13 Spanish hospitals. Patients ≥18 years-old diagnosed with PA or SpA were selected. Patients receiving biologics or systemic steroids were excluded. Among patients ≥ 50 years, only those without valid colonoscopy in the previous 3 years were included. Rheumatologists performed a baseline visit and collected demographic, clinical data. Fecal calprotectin (FC) was determined by the Quantum Blue rapid test and this was followed by a gastroenterologist consultation. Figure 1 summarizes study protocol.

Results
A total of 559 patients were included (51% men; mean 52.2 years; mean disease duration of SpA/PA was 12.3 years). The most frequent disease was radiographic SpA (37%), followed by peripheral APs (36%). Tabla 1 shows demographic characteristics of patients. A total of 40% of patients has FC ≥ 80 ug/g. In the multivariate logistic regression analysis factors associated with a greater likelihood of FC ≥ 80 µg/g were disease duration (OR 1.021, 95%CI 1.000 to 1.042, p&lt;0.05) and disease activity by ASDAS-CRP (OR 2.158, 95%CI 0.906 to 5.139, p&lt;0.1), while general health status by EQ-5D-5L was associated with a lower likelihood of FC ≥ 80 µg/g (OR 0.976, 95%CI 0.960 to 0.993, p&lt;0.01). 28 patients were diagnosed of IBD, leading to a prevalence of 5.7%, 22 out of the 248 patients with axial SpA had IBD (8.9%) and 6 out of the 246 patients with PsA (2.4%). 24 were diagnosed with Crohn’s disease (CD), 3 unclassified IBD, and 1 UC. Seven (25.0%) of these IBD patients showed symptoms. The ROC curve for FC and the diagnosis of IBD is presented in Figure 1 (AUC of 0.870 (p&lt;0.001, 95CI% 83.7 to 89.8). The highest sensitivity(S) and specificity (Sp) corresponded to a FC level &gt;147 µg/g (S= 85.7% and a Sp of 75.5%, a PPV of 17.4% (95%CI 14.5 to 20.8) and NPV of 98.9% (95%CI 97.3 to 99.5).

Conclusion
- 5.7% of SpA patients have undiagnosed IBD. This prevalence was higher among axial SpA than PsA patients.
- CD is the most frequent IBD type observed.·
- FC is a useful tool to identify patients with SpA and lesions secondary to IBD.
- FC has a high NPV to rule out IBD in axial SpA patients.
- Disease duration, quality of life and disease activity of SpA are associated with higher levels of FC.