Correlation Between IgA Tissue Transglutaminase Antibody Ratio and Histological Finding in Celiac Disease

ABSTRACT Objectives: Positivity of both immumoglobulin A anti‐tissue transglutaminase (TTG) and anti‐endomysium antibodies (EMA) has a positive predictive value of nearly 100% for celiac disease (CD). The objective of the present study was to evaluate whether patients of any age, with high pretest probability of CD and high titre of anti‐TTG and EMA positivity, have a high probability of intestinal damage and may not require the biopsy for final diagnosis. Methods: A retrospective analysis of 412 consecutively referred patients, age range 10 months to 72 years, who underwent small‐bowel biopsy for suspicion of CD and positivity to both anti‐TTG and EMA, was performed at 4 Italian centers. Biopsies were evaluated independently by 2 pathologists using Marsh modified classification; in cases of dissimilar results, a third pathologist examined the biopsy. The final histological finding diagnosis was expressed as the prevalent or highest score assigned by the pathologist board. Results: Three hundred ninety‐six patients (96.1%) had histological findings consistent with CD (grade 2 and 3a, 3b, or 3c of modified Marsh classification). An anti‐TTG ratio ≥7 was able to identify with the 3 assays used (Celikey, anti‐TTG immumoglobulin A, EuTTG) all of the patients with significant mucosal damage (Marsh ≥2) independent of age and sex; specificity and positive predictive value were 100%. An anti‐TTG ratio >20 was more specific (99.8%) for identification of patients with villous atrophy (Marsh 3 a, b, or c). Conclusions: Patients with positivity of anti‐TTG ≥7‐fold cutoff, confirmed by positivity to EMA, have a high‐degree probability of duodenal damage. In selected conditions, a duodenal biopsy may be avoided and a confirmed greatly positive anti‐TTG result could be the basis to prescribe a gluten‐free diet.