P267 Redefining the diagnosis of type 1 refractory coeliac disease using urine gluten immunogenic peptides

Introduction Refractory Coeliac Disease (RCD) is defined as ongoing symptoms or signs of malabsorption with associated villous atrophy (VA) despite strict adherence to a gluten free diet (GFD). However, assessment of dietary adherence is challenging. The utility of urine gluten immunogenic peptides (GIP) in patients with RCD1 was assessed for the first time in the literature. Methods 2553 patients with coeliac disease (CD) were reviewed at Sheffield Teaching NHS Foundation Trust between 1998 and 2019. 5.1% (n=103) of patients had RCD, with 64.1% (n=66) of these being classified as RCD1, and 35.9% (n=37) being classified as RCD2/complicated coeliac disease (CCD). From the RCD1 cohort, 22 patients (33.3%) were successfully treated with budesonide, with 44 patients (66.7%) having ongoing VA. All of these patients had had a dietetic review suggestive of good GFD adherence. RCD1 patients with ongoing VA (n=44) were invited to complete three gluten immunogenic peptides (GIP) tests, using rapid immunochromatographic testing, following the collection of mid-stream urine samples. Ongoing gluten ingestion was defined as having at least one weak positive/positive urine GIP sample. Results At diagnosis, RCD 1 patients were significantly younger than RCD2/CCD patients (p=0.002). 38 RCD1 patients with ongoing VA were recruited (71.1% female [n=27], median age 60 years). 52.6% (n=20) of patients with RCD1 had three negative GIP tests, suggestive of strict GFD adherence. However, 47.4% (n=18) had at least one positive GIP result, suggestive of possible ongoing gluten exposure. Conclusions A high proportion of individuals with RCD1 appear to have ongoing gluten exposure despite reported strict GFD adherence, as assessed by urine GIP. Urine GIP may re-define and enable the accurate diagnosis of RCD1 in the future.