Objectives: The aim of the present study was to evaluate diagnostic performance and actual costs in clinical practice of immumoglobulin (Ig)G/IgA deamidated gliadin peptide antibodies (DGP) as a complement to IgA antibodies against tissue transglutaminase (tTG) for the diagnosis of pediatric celiac disease (CD).
Methods: All of the consecutive patients younger than 18 years tested for tTG and/or DGP, who underwent duodenal biopsy because of suspected CD in Stockholm and Gothenburg, Sweden, from 2008 to 2010, were included. Medical records were reviewed.
Results: Of 537 children who underwent duodenal biopsy, 278 (52%) had CD. A total of 71 (13%) were younger than 2 years and 16 (4%) had IgA deficiency. Sensitivity and specificity for tTG were 94% and 86%, respectively. Corresponding values for DGP were 91% and 26%. Positive predictive values (PPV) were 88% for tTG and 51% for DGP. There were 148 children who were tTG-negative and DGP-positive, of which only 5% (8/148) had villous atrophy. Among children younger than 2 years with normal IgA, PPV was 96% (25/26) for tTG and 48% (24/50) for DGP. In 16 IgA-deficient children, 11 were DGP positive, of which 5 had CD (PPV 45%). Eight of 278 cases of CD would possibly have been missed without DGP. The cost of adding DGP and consequently more biopsies to be able to detect 8 extra cases of CD was €399,520 or €49,940 per case.
Conclusions: For diagnosing CD, tTG is superior to DGP, even in children younger than 2 years. Combining tTG and DGP does not provide a better tradeoff between number of missed cases of CD, number of unnecessary duodenal biopsies, and cost than tTG alone.