Tests to measure serum endomysial antibodies (EMA) and antibodies to tissue transglutaminase (tTG) were developed to screen for celiac disease in patients consuming gluten.
However, they are commonly used to monitor patients on a gluten-free diet.
Dr Donald Duerksen and colleagues conducted a meta-analysis to assess the sensitivity and specificity of tTG IgA and EMA IgA assays in identifying patients with celiac disease who have persistent villous atrophy despite a gluten-free diet.
The team searched PUBMED, EMBASE, BIOSIS, SCOPUS, clinicaltrials.gov, Science Citation Index, and Cochrane Library databases through 2016.
Inclusion criteria were studies of subjects with biopsy-confirmed celiac disease, follow-up biopsies, and measurement of serum antibodies on a gluten-free diet , biopsy performed on subjects regardless of symptoms, or antibody test results.
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The researchers excluded subjects with refractory celiac disease, undergoing gluten challenge, or consuming a prescribed oats-containing gluten-free diet.
Tests were considered to have positive or negative findings based on manufacturer cut-off values.
The team defined villous atrophy as a Marsh 3 lesion or villous height:crypt depth ratio below 3.0.
The researchers constructed forest plots to determine the sensitivity and specificity of detection for individual studies.
For the meta-analysis, a bivariate random effects model was used to jointly model sensitivity and specificity.
The team's search identified 5408 unique citations.
Following review of abstracts, 442 articles were reviewed in detail.
The research team reported that only 26 studies met the inclusion criteria.
The most common reason studies were excluded from our analysis was inability to cross-tabulate histologic and serologic findings.
The serum assays identified patients with persistent villous atrophy with high levels of specificity, at 0.83 for the tTG IgA assay, and 0.91 for the EMA IgA assay.
However, they detected villous atrophy with low levels of sensitivity, at 0.50 for the tTG IgA assay and 0.45 for the EMA IgA assay.
The team observed that the tests had similar levels of performance in pediatric and adult patients.
Dr Duerksen's team concludes, "In a meta-analysis of patients with biopsy-confirmed celiac disease undergoing follow-up biopsy on a gluten-free diet, we found that tests for serum tTG IgA and EMA IgA levels had low sensitivity in detection of persistent villous atrophy."
"We need more-accurate non-invasive markers of mucosal damage in children and adults with celiac disease who are following a gluten-free diet."