P337 Low seroprevalence of celiac disease in a large screening study in unselected Swiss IBD cohort patients

Several systematic screening studies in the general population indicate a high number of unrecognised cases of Celiac disease (CeD). According to clinical experience and shared risk gene loci CeD and inflammatory bowel disease (IBD) may be associated conditions. However, the exact prevalence of asymptomatic and unrecognised CeD in IBD has not been systematically investigated on the large scale. We performed a large screening-study of the CeD seroprevalence in unselected IBD patients from the Swiss IBD Cohort study (SIBDCS). Anti-tissue transglutaminase (a-TTG) antibody IgA, anti-deamidated gliadin peptide IgG (g-DGP) and total serum immunoglobulin A were measured. In total serum samples of 2019 IBD patients (median disease duration 12 years, median age at enrolment into the SIBDCS 38 years, median BMI 24 kg/m2)were analysed, among them 1150 (57.3%) with Crohn’s disease (CD), 812 (40.5%) with ulcerative colitis UC and 45 (2.2%) with IBD unclassified (IBDu). In 8 (4 per mille) of the 2019 randomly selected SIBDCS patients a diagnosis of CeD had been established previously. Amongst the remaining 2011 IBD patients without CeD we found a seroprevalence of 1.5 per mille (0.149%) for a-TTG—the classical screening test in the absence of IgA deficiency—and 1 per mille (0.099%) for g-DGP. IgA deficiency (defined as <0.07 g/l) was detected in 4 per mille (0.398%). Importantly, the prevalence of a-TTG and g-DGP was not different in patients with vs. without immunosuppressive treatment. The overall prevalence of potential undiagnosed CeD in our SIBDCS collective according to presence of either g-DGP or aTTG (excluding known CeD cases) was 2 per mille (0.199%), whereas the overall CeD prevalence (composite of either the former or established CeD) was 4.5 per mille (0.446%). This is, to the best of our knowledge, the largest study on CeD seroprevalence in IBD to date, showing that the fraction of undiagnosed positive CeD-serology in IBD patients is very low. In contrast to several previous mostly single-centre reports on a potential higher occurrence of CeD (and in concordance with other such investigations not having found a higher CeD prevalence), the fraction of undiagnosed CeD cases in IBD patients appears to be exceedingly lower than those found in systematic screening studies on CeD prevalence in the general population. Our results do not warrant a widespread CeD screening in IBD patients.