Serological markers for coeliac disease: is it time to change?

Background: Anti-gliadin and anti-endomysium antibodies are useful markers in the screening and follow-up of coeliac disease. The recent finding that tissue transglutaminase is the main auto-antigen of anti-endomysium has led to the discovery of anti-tissue transglutaminase antibodies.
Aim: To compare, in a prospective study, the diagnostic accuracy of anti-tissue transglutaminase, anti-gliadin and anti-endomysium antibodies in a large series of adult patients.
Methods: The study involved 80 consecutive subjects undergoing upper gastrointestinal tract endoscopy for suspected coeliac disease (subsequently confirmed in 40 cases), 195 coeliac patients on a gluten-free diet, and 70 patients with different gastrointestinal disor ders and normal duodenal histology. Anti-gliadin, anti-endomysium and anti-tissue transglutaminase antibodies levels were measured using commercial kits.
Results: The diagnostic sensitivity and specificity of anti-gliadin, anti-endomysium and anti-tissue transglutaminase antibodies were, respectively, 95% and 89.1%, 100% and 97.3%, and 100% and 98.2%: the agreement between the markers was substantial or almost perfect. In terms of follow-up, the positivity of the markers varied according to the strict adherence to, and duration of the gluten-free diet; the agreement between antiendomysium and anti-tissue transglutaminase antibodies was almost perfect.
Conclusions: Anti-endomysium and anti-tissue transglutaminase antibodies are both highly efficient for routine laboratory screening: the choice of one or the other will depend on the available facilities. However, neither can replace intestinal biopsy for general population screening because, in this case, their respective positive predictive values are only 15.7% and 21.8%. During follow-up, anti-gliadin retain their value as an early predictor of gluten ingestion.