WHAT IS THE ROLE OF NOVEL URINARY MARKERS WHEN ASSESSING PATIENTS WITH ADULT COELIAC DISEASE?

Introduction

A gluten-free diet (GFD) is the primary treatment for patients with coeliac disease. The current options for checking adherence are through dietary questionnaires and serological markers (IgA-tTG and IgA-EMA), however a recent meta-analysis showed a poor relationship between serological markers & the presence of villous atrophy. Novel gluten immunogenic peptides (GIP), resistant to gastrointestinal digestion, can be measured in urine and stool. We are presenting the largest data set looking at the relationship between dietary questionnaires (assessing for exposure to gluten), serology and urinary markers for GIP in adult patients with coeliac disease.

Methods

We assessed adult patients being investigated for coeliac disease (n= 105) with a gastroscopy and duodenal biopsy and adult patients with known coeliac disease (n=172) having a biopsy to assess for remission. Patients had concurrent biopsies, serological testing and urinary GIP. For patients with established coeliac disease, dietary adherence questionnaires were also used (Biagi & CDAT).

Results

In total, 277 patients were recruited (71% female, median 57years). A positive GIP significantly correlated to a positive IgA-EMA, IgA-tTG and the presence of villous atrophy (p<0.005, p=0.03 and p<0.005 respectively). Results of both adherence questionnaires were similar to each other (p=0.03) but neither CDAT or Biagi correlated to a positive IgA-EMA (p=0.35 and p=0.25 respectively), or a positive IgA-tTG (p=0.37 and p=0.51 respectively), or a positive GIP (p=0.53 and p=0.50 respectively), or the presence of villous atrophy (p=0.61 and p=0.15 respectively). Combining GIP and serological markers for recognising villous atrophy had a sensitivity, specificity, PPV and NPV of 53%, 88%, 90% and 47% respectively.

Conclusion

There is poor agreement between self-reported adherence to a GFD and serological or urinary markers; this suggests that patients may not be aware of their exposure to gluten or are deliberately not disclosing gluten ingestion. Serological and urinary markers are more accurate than questionnaires for recognising non-adherence to a GFD.