TOPLINE:
For adults with suspected celiac disease who do not have immunoglobulin A (IgA) deficiency, diagnostic bowel biopsy can most likely be avoided if the serum anti-tissue transglutaminase IgA (tTG-IgA) level is low.
METHODOLOGY:
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Researchers evaluated the reliability of serum tests for diagnosing celiac disease, as defined by duodenal villous atrophy (Marsh type 3 or Corazza–Villanacci grade B).
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The main study cohort included 436 adults with suspected celiac disease who did not have IgA deficiency and who were not on a gluten-free diet (mean age, 40 years; 68% women). The patients were referred by 14 centers across four continents to undergo local endoscopic duodenal biopsy.
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Local serum tTG-IgA was measured with 14 test brands. Concentration was expressed as a multiple of each test’s upper limit of normal (ULN). Tests were defined as positive when they exceeded 1 times the ULN.
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Histology was assessed by the local pathologist, and discordant cases were reevaluated by a central pathologist.
TAKEAWAY:
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Positive serum tTG-IgA was detected in 363 (83%) participants; negative serum tTG-IgA was detected in 73 (17%).
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After local review, 341 of the participants with positive serum tTG-IgA had positive histology (true positives) and 22 had negative histology (false positives).
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Of the 73 participants with negative serum tTG-IgA, 66 had negative histology (true negatives) and seven had positive histology (false negatives).
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Central reevaluation of duodenal histology was performed in 29 discordant cases, resulting in 348 true positive cases, 15 false positive cases, 66 true negative cases, and seven false negative cases ― the equivalent of a positive predictive value of 95.9%, a negative predictive value of 90.4%, a sensitivity of 98%, and a specificity of 81.5%.
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The positive predictive value of local serum tTG-IgA increased when the serologic threshold was defined at increasing multiples of the ULN. The test correctly diagnosed duodenal villous atrophy in 97.5% of patients with serum tTG-IgA concentrations greater than 10 times the ULN.
IN PRACTICE:
“The results of this multicentre prospective study indicate that a no-biopsy approach for the diagnosis of coeliac disease is safe and reliable in adult patients without IgA deficiency and with serum tTG-IgA greater than the assay-specific upper limit of normal,” the authors write. “We found no evidence that important comorbidities would be missed by adopting a no-biopsy strategy.”
SOURCE:
The study was led by Carolina Ciacci, Centre for Coeliac Disease, AOU San Giovanni Di Dio e Ruggi d’Aragona, Salerno, Italy, and was published online September 8 in The Lancet Gastroenterology and Hepatology.
LIMITATIONS:
Limitations include a lack of data on IgA-deficient participants, a low number of participants in some subgroup analyses, a lack of data for many ethnic groups, limited follow-up information, limited assessments in the central laboratory, and high pretest probability of celiac disease (low number of participants without duodenal villous atrophy).
DISCLOSURES:
The study had no specific funding. One co-author is an employee of Werfen. The other authors have disclosed no relevant financial relationships.
Follow Marilynn Larkin on X: @MarilynnL.
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