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Need for quantitative assessment of transglutaminase autoantibodies for celiac disease in screening-identified
Edwin Liu1, Marcella Li, Fei Bao
1Davis Center for Childhood Diabetes, School of Medicine, University of Colorado Health Sciences Center, 4200 East Ninth Avenue, Denver, CO 80262, USA.
Insights
Transglutaminase autoantibody (TGAA) assays show high false-positive rates in children at risk for celiac disease (CD). Increasing assay cutoffs improves positive predictive value, but standardization is needed.
Area of Science:
- Pediatric gastroenterology
- Immunology
- Diagnostic assay development
Background:
- Celiac disease (CD) diagnosis relies on serological markers and intestinal biopsy.
- Transglutaminase autoantibody (TGAA) assays are key screening tools.
- Assay variability can impact diagnostic accuracy, especially in at-risk pediatric populations.
Purpose of the Study:
- To evaluate the performance of multiple TGAA assays in distinguishing CD in children with abnormal versus normal intestinal biopsies.
- To assess the positive predictive value (PPV) and false-positive rates of various TGAA assays in a pediatric cohort at high risk for CD.
Main Methods:
- A cohort of 54 children at risk for CD (type 1 diabetics, relatives, HLA-DQ2+) underwent intestinal biopsy.
- Sera were tested for TGAA using radioimmunoassay and five enzyme-linked immunosorbent assays (ELISAs).
Main Results:
- False-positive rates varied widely across assays, from 28% to 80%.
- PPV ranged from 63% to 84%, lower than in symptomatic children.
- Elevating the cutoff for each assay significantly improved PPV.
Conclusions:
- Significant quantitative differences exist among TGAA assays, affecting CD interpretation.
- High false-positive rates were observed in this at-risk pediatric population.
- Standardization through multicenter workshops is crucial for reliable TGAA assay performance.
Objectives:
To assess several transglutaminase autoantibody (TGAA) assays in their ability to distinguish celiac disease (CD) in screening-identified children with abnormal intestine biopsy specimens from those with normal biopsy specimens.
Study Design:
Children at risk for CD (n = 54) composed of type 1 diabetics, first-degree relatives of type 1 diabetics or CD, and HLA-DQ2+ individuals followed from birth received intestine biopsy. Sera obtained at the time of biopsy were tested for TGAA, using the radioimmunoassay and 5 other commercially available enzyme-linked immunosorbent assays.
Results:
False-positive rates ranged from 28% to 80%. The positive predictive value (PPV) of the tests ranged from 63% to 84% (lower than reported for symptomatic children). Setting a higher cutoff for each assay maximized PPV.
Conclusions:
There are significant quantitative differences among all TGAA assays that could affect interpretation of a positive test for CD. The overall false-positive rate for all assays was high in this population. Using the assay as a quantitative rather than qualitative tool by increasing the cutoff of positivity to indicate biopsy increases PPV. Multicenter workshops are needed to identify critical differences and to standardize TGAA assays among laboratories.
