Isolated positive deamidated gliadin peptide‐IgG has limited diagnostic utility in coeliac disease

AIM: Deamidated gliadin peptide‐IgG (DGP‐IgG) antibody serology testing is widely utilised in screening for coeliac disease in Australia; however, it is used sparingly in Europe. The aim of this study was to assess the diagnostic value of a positive DGP‐IgG in the setting of a negative tissue transglutaminase‐IgA (tTG‐IgA) for gastrointestinal pathology among paediatric patients. METHODS: We conducted a retrospective cohort study of all children with an elevated DGP‐IgG in the setting of a negative tTG‐IgA who underwent gastroscopy over a 48‐month period (January 2015–December 2018) at a tertiary paediatric centre. They were identified utilising the electronic pathology database and demographic and clinical data were collected from electronic medical records. Patients who had previously been diagnosed with coeliac disease were on a gluten‐free diet or over the age of 18 were excluded from the study. RESULTS: Twenty‐six patients with an elevated DGP‐IgG in the setting of a negative tTG‐IgA underwent gastroscopy. Our study yielded a positive predictive value of 1/26 (3.9% CI 95% 0.7%, 18.9%) for the diagnosis of coeliac disease. Overall, there were 25 histopathological diagnoses including 1 diagnosis of coeliac disease among the total 26 patients who were positive DGP‐IgG and negative tTG‐IgA and underwent gastroscopy. CONCLUSIONS: Our findings suggest that an isolated positive DGP‐IgG has a very low diagnostic yield for coeliac disease in children and may be indicative of other gastrointestinal pathology.