Serological screening for coeliac disease in an adult general population: the HUNT study.

Background: A large proportion of individuals with coeliac disease (CeD) remain undiagnosed.
Objective: The aim of this study was to assess serological screening for CeD in the adult general population.
Design: The study was based on the fourth Trøndelag Health Study, a population-based study performed 2017-2019 in Nord-Trøndelag County, Norway, including 56 042 participants >20 years of age (54% participation rate). Serum samples were analysed with a dual antitransglutaminase 2 (TG2) IgA and IgG assay and seropositive participants were invited to endoscopy with duodenal biopsies. A CeD diagnosis was given if mucosal damage (Marsh grade 3) was found.
Results: Histological evaluation of 657 seropositive participants confirmed CeD in 423. The positive predictive value (PPV) of a positive TG2 IgA was 73.3% (95% CI 69.7% to 77.0%) for biopsy-confirmed CeD. TG2 IgA ≥10 times the upper limit of normal (ULN), as used in the no-biopsy approach in children, increased the PPV to 88.1% (95% CI 84.8% to 91.4%). Primary TG2 IgG response was found in 87 participants, five of whom had biopsy-confirmed CeD. One of the participants with CeD primarily responding with TG2 IgG was IgA deficient. The PPV of a positive TG2 IgG was 5.8% (95% CI 1.9% to 12.9%) and of TG2 IgG ≥10× ULN was 9.5% (95% CI 1.2% to 30.4%) for biopsy-confirmed CeD in TG2 IgA-negative individuals.
Conclusion: The TG2 IgA assay showed excellent abilities as a screening tool for CeD in the adult general population. However, the diagnostic accuracy of TG2 IgG was too poor for selectively identifying individuals with CeD.
Competing Interests: Competing interests: None declared.
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