Celiac Disease Diagnosis Without Biopsy: is a 10x uln Anti-transglutaminase Result Suitable for a Chemiluminescence Method?

OBJECTIVES:2012 ESPGHAN guidelines allow to establish a celiac disease (CD) diagnosis without duodenal biopsy in symptomatic pediatric patients with anti-tissue transglutaminase (anti-tTG) titers > 10 times the upper limit of normal (ULN). For some years now, new chemiluminescence immunoassays have been made availableit is important to establish the clinical performance of anti-tTG and to determine the cut-off best suited to predict Marsh ≥ 2 in order to avoid gastrointestinal endoscopy not only in children, but also in the adult population. METHODS:2565 patients performed duodenal biopsy from July 2012 to September 2016; we selected all the patients who had undergone QUANTA Flash® anti-tTG IgA within +/− 3 months of duodenal biopsy and before the start of gluten free diet. 827 patients fulfilled the criteria for selection. RESULTS:Using a cut-off of 20 CU (Area Under the Curve0.995), sensitivity, specificity, positive and negative predictive value were 98.2%, 98.4%, 97.9% and 98.6%, respectively. For the correlation with Marsh ≥2, in the pediatric population, Positive Predictive Values (PPV) was 92.1%, 99% and 100% at 200 CU(10x), 560 CU (28x) and 1000 CU(50x) respectively. In the adult population PPV was 94.2%, 98.2% and 100% at 200 CU (10x), 350 CU (15x) and 400 CU(20x). CONCLUSIONS:Sensitivity, specificity, positive and negative predictive value of QUANTA Flash® h-tTG IgA were excellent. The cut-off providing an optimized PPV for histological lesions compatible for CD (Marsh ≥2) for the QUANTA Flash® h-tTG IgA is 350 CU (15x) in adult and 560 CU (28x) in children.