Are We Meeting Celiac Disease Benchmarks in Inflammatory Bowel Disease Patients With Celiac Disease? Evaluation of Clinical, Serological, and Histological Characteristics: Case-Control Study From a Tertiary Referral Center

Introduction: A small portion of Inflammatory bowel disease (IBD) subjects have celiac disease (CeD). We conducted a retrospective case-control study to compare disease characteristics of subjects with IBD+ CeD vs CeD. Methods: Patients were screened from January 2017 until June 2022 using appropriate ICD-10 codes for IBD and CeD. Data was collected including demographics, gluten-free diet (GFD) adherence patterns, celiac disease symptom index (CSI), serologic and histologic remission of CeD, from earliest available until time of administrative censoring. Results: 80 subjects with CeD and 36 subjects with IBD+ CeD were included. 70% of CeD and 64% of IBD+ CeD subjects were female (P=0.54). The median age at diagnosis of CeD in the CeD and IBD+ CeD subjects was similar. There was a higher rate of self-taught (83%), internet-taught (14%), or book-taught (14%) initiation of GFD in the IBD+ CeD group as compared to 50%, 0%, and 1% respectively in the CeD group (all p£0.01). Dietician referral was low in both groups (< 22%). The prevalence of the following components of the CSI were more frequently reported in IBD+ CeD: abdominal pain (89%), nausea and vomiting (58%), bloating (58%), diarrhea (89%), and weight loss (78%) when compared to 53%, 29%, 29%, 48%, and 13% in CeD, respectively (all p£0.01). Other significant co-morbidities that were notably more common in IBD+ CeD include unexplained anemia (47%), malnutrition (19%), arthritis (8%), and rheumatoid arthritis (RA) (8%) when compared to CeD group at 21%, 1%, 4%, 0%, respectively (P< 0.05). The median and IQR serum tTG IgA titers dropped consistently over a 5-year timeline in both groups (Figure 1a). Kaplan-Meir (KM) curves indicated a similar estimated survival probability by log rank test of Marsh Score remaining 1 or below at 2 years in the IBD+ CeD group when compared to CeD group (Figure 1b) (P=0.37) over the observed period of years since first GFD start date. No subjects with IBD+ CeD had follow-up duodenal biopsies beyond 2 years. Conclusion: Only 20% of IBD+ CeD were referred to a dietician for initiation of a GFD. Further, CSI burden and associated co-morbid conditions were higher in IBD+ CeD group. Very few IBD+ CeD underwent duodenal biopsy beyond 2 years and celiac serologies beyond 5 years. This study highlights the need for clinicians to objectively assess celiac disease activity and GFD adherence, especially in IBD+ CeD with high CSI symptom burden (see Table 1).Figure 1.: (A) Comparison of serum tTG IgA titers between CeD and IBD+ CeD over the course of follow up. (B) Kaplan-Meir curve demonstrating the estimated survival probability by log rank testing of Marsh score remaining 1 or below in CeD and IBD+ CeD. Table 1. - Comparison of CeD Baseline Characteristics between CeD+IBD and CeD Variable CeD (N=80) CeD+IBD (N=36) P-value Female 55 (69.6%) 23 (63.9%) 0.542 Age at CeD diagnosis median (IQR) 36.0 (22.0, 45.0) 25.5 (19.0, 54.5) 0.664 Duration of CeD median (IQR) 6.2 (3.5, 9.2) 5.1 (2.1, 7.9) 0.228 Age at end of study median (IQR) 41.1 (29.5, 51.6) 34.1 (26.2, 58.3) 0.433 Duration of GFD median (IQR) 6.1 (2.9, 9.2) 5.2 (2.5, 7.0) 0.352 Mechanism of GFD Education, n (%) Self-taught 40 (50.0%) 30 (83.3%) < 0.001 Internet 0 (0%) 5 (13.9%) 0.002 Book 1 (1.3%) 5 (13.9%) 0.011 Dietician 17 (21.3%) 6 (16.7%) 0.567 Celiac Dietician 0 (0%) 0 (0%) Other 18 (22.5%) 3 (8.3%) 0.067 CeD Symptoms Present, n (%) Unexplained anemia 17 (21.3%) 17 (47.2%) 0.004 IgA Deficiency 1 (1.3%) 0 (0%) 1.000 Malnutrition 1 (1.3%) 7 (19.4%) 0.001 Abdominal Pain 42 (52.5%) 32 (88.9%) < 0.001 Nausea/vomiting 23 (28.8%) 21 (58.3%) 0.002 Bloating 23 (28.8%) 21 (58.3%) 0.002 Constipation 18 (22.5%) 8 (22.2%) 0.974 Diarrhea 38 (47.5%) 32 (88.9%) < 0.001 Weight loss 10 (12.5%) 28 (77.8%) < 0.001 Weight gain 10 (12.5%) 3 (8.3%) 0.752 Arthritis 4 (5.0%) 8 (22.2%) 0.008 Fibromyalgia 2 (2.5%) 4 (11.1%) 0.074 Rheumatoid Arthritis 0 (0%) 3 (8.3%) 0.028 Thyroiditis 7 (8.8%) 6 (16.7%) 0.220 Type 1 DM 6 (7.5%) 1 (2.8%) 0.433