Utilizing both IgA tissue transglutaminase and IgG-deamidated gliadin peptide antibodies offers accurate celiac disease diagnosis without duodenal biopsy

Background: Gastroenterologists still raise concerns about adopting a non-biopsy strategy for diagnosing celiac disease (CeD) in adults. Aim: To assess the performance of the concurrent detection of two autoantibodies targeting two independent antigens, tissue transglutaminase (tTG) and deamidated gliadin peptides (DGP). Methods: This prospective, multicenter, binational study collected consecutive patients with a high pre-test probability for CeD. Between 2018 and 2020, adults were enrolled at four Italian and one Argentinian center. Serology was also blindly analyzed by a central laboratory (Werfen, San Diego, USA) for tTG IgA and DGP IgG by Aptiva Particle-based multi-analyte technology (PMAT) assays. CeD diagnosis required histological confirmation of Marsh 3 damage. Results: 181 adult patients with suspected CeD were enrolled (134 with histological diagnosis of CeD and 47 not histologically confirmed as CeD). Patients positive for both tTG IgA and DGP IgG (double positive) were predictive of CeD in 92.5 % of patients at >1x upper limit of normal (ULN). Double positivity for tTG IgA and DGP IgG, both at >10x ULN, had a 100 % positive predictive value for the presence of Marsh 3 histology. Conclusions: Incorporating DGP IgG alongside tTG IgA in a single-step approach can be considered a valid confirmatory strategy for definitive non-biopsy diagnosis of CeD.