Increased Detection of Celiac Disease with Measurement of Deamidated Gliadin Peptide Antibody Before Endoscopy

Celiac.com 08/20/2015 - Celiac disease is frequently mis-diagnosed. Even when patients received endoscopy, celiac disease is often missed or not detected.

A team of researchers recently assessed the accuracy of finger prick-based point-of-care tests in the detection of celiac disease, and developed an algorithm for diagnosis.

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The research team included PD Mooney, SH Wong, AJ Johnston, M Kurien, A Avgerinos, and DS Sanders. They are variously affiliated with the Royal Hallamshire Hospital, Sheffield, United Kingdom and the University of Sheffield, Sheffield, United Kingdom.

Their team conducted a prospective study of two groups of celiac disease patients evaluated at the Royal Hallamshire Hospital in Sheffield UK from March 2013 through February 2014.

In group one, the team evaluated 55 patients at high risk for celiac disease, and who tested positive for endomysial antibody, using the Biocard test (BHR Pharmaceuticals, Nuneaton, UK) and the Celiac Quick Test (Biohit Healthcare UK, Ellesmere Port, UK), which measure antibodies to tissue transglutaminase (anti-tTG), and the Simtomax test (Tillotts Pharma, Rheinfelden, Switzerland), which measures deamidated gliadin peptide antibodies (DGP).

Group 2 included 508 consecutive patients who received an endoscopy for any reason, received the DGP test, and also were evaluated using a diagnostic algorithm that incorporated results from the DGP test and data on symptoms.

For both groups, point-of-care tests were administered at the time of endoscopy, and the results compared against results from histologic analyses of duodenal biopsy specimens from all patients.

In group 1, the DGP test identified patients with celiac disease with 94.4% sensitivity, the Celiac Quick Test identified patients with 77.8% sensitivity (P = .03 vs the DGP test), while the Biocard test identified patients with 72.2% sensitivity (P = .008 vs the DGP test).

In group 2, the DGP test identified patients with celiac disease with 92.7% sensitivity (95% confidence interval, 83.0-97.3), 85.2% specificity (95% confidence interval, 81.5-88.3), a positive predictive value of 49.2% (95% confidence interval, 40.3-58.2), and a negative predictive value of 98.7% (95% confidence interval, 96.8-99.5).

Measurement of serum anti-tTG identified patients with celiac disease with 91.2% sensitivity (95% confidence interval, 81.1-96.4), 87.5% specificity (95% confidence interval, 84.0-90.4), a positive predictive value of 53.0% (95% confidence interval, 43.6-62.2), and a negative predictive value of 98.5% (95% confidence interval, 96.5-99.4).

The algorithm identified patients with celiac disease with 98.5% sensitivity, and has the potential to reduce duodenal biopsies by 35%. In this prospective study, the test for DGP identified celiac patients with comparable sensitivity and specificity as standard serologic analysis of anti-tTG.

Conducting the DGP test before endoscopy might increase the accuracy of the diagnosis of celiac disease.

These results look promising, but further study is needed, in lower-prevalence populations, to more accurately determine the potential benefits of the DGP test in celiac screening.

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