Pacheco, M. Cristina

BACKGROUND AND OBJECTIVES Recent changes in European diagnostic criteria allow for serologic diagnosis of celiac disease in children. Those guidelines have not been adopted in North America; hence, we aim to assess the positive predictive value (PPV) of tissue transglutaminase (tTG) immunoglobulin A (IgA) assays used in North America in identifying histologic findings of celiac disease. METHODS Multicenter retrospective cohort study of children (<18 years) with an elevated tTG IgA within 6 months of an esophagogastroduodenoscopy between January 2016 and December 2021. Biopsy-confirmed celiac disease was determined by the presence of intraepithelial lymphocytosis and villous atrophy. The primary outcomes were the PPV of an elevated tTG IgA and tTG IgA greater than or equal to 10 times the upper limit of normal (10× ULN). RESULTS Overall, 4019 children (63.3% female; 9% type 1 diabetes, 2% Down syndrome) were included. Histologic findings were consistent with celiac disease for 3321 children (PPV = 82.6% [95% CI, 81.4–83.8]). Among the 1739/4019 (43.2%) children with tTG IgA greater than or equal to 10× ULN, 1651 had biopsy-confirmed celiac disease (PPV10× = 94.9% [95% CI, 93.8–95.9]). Five percent (88/1739) of children did not have histologic findings of celiac disease, including 41/1739 (2%) with normal histology. Diagnostic accuracy of tTG IgA varied widely among assays used in North America (PPV range: 71.5%–88.8%; PPV10× range: 89.3%–97.3%). Assays performed worse in children with type 1 diabetes (PPV10× 89% [95% CI, 83.5–92.8]). CONCLUSIONS Elevated tTG IgA in isolation is insufficient to confidently diagnose celiac disease. As tTG assay performance varied widely, diagnostic confirmation by a specialist prior to dietary changes is essential.

Validated nonbiopsy methods to assure duodenal mucosal healing in celiac disease are lacking, yet ongoing mucosal injury is associated with anemia, osteoporosis, and lymphoma. Most providers utilize clinical data as surrogates of mucosal status to avoid additional esophagogastroduodenoscopy. The reliability of such surrogates to predict mucosal recovery has been incompletely evaluated. The aim of this study was to rigorously assess patterns of histologic mucosal recovery at follow-up in celiac disease and to correlate findings with clinical data. Gastrointestinal pathologists from 13 centers evaluated initial and follow-up duodenal biopsies from 181 celiac disease patients. Marsh scores and intraepithelial lymphocytes (IELs)/100 enterocytes were assessed blindly. Histology at follow-up was correlated with symptoms, immunoglobulin A anti–tissue transglutaminase titers and gluten-free diet adherence. Fifty-six/181 (31%) patients had persistent villous blunting and 46/181 (25%) patients had just persistently elevated IELs at follow-up, with only 79/181 (44%) patients having complete histologic remission. IEL normalization (82/181; 45%) lagged villous recovery (125/181;69%). In a minority of patients, villous blunting was limited to proximal duodenal biopsies. No correlation was found between Marsh scores and symptoms, normalization of immunoglobulin A anti–tissue transglutaminase serology, or diet adherence. Children showed greater recovery of Marsh score (P<0.001) and IELs (P<0.01) than adults. Persistent mucosal injury is common in celiac disease, with discordant villous/IEL normalization. Pathologist awareness of expected findings in celiac disease follow-up biopsies, including their frequent lack of correlation with clinical data, is important for patient management, and has implications for eligibility criteria for therapeutics currently in development.