Antibodies Against Deamidated Gliadin Peptides and Tissue Transglutaminase for Diagnosis of Pediatric Celiac Disease - Diagnostic Performance and Cost in Clinical Practice.

OBJECTIVES: To evaluate diagnostic performance and actual costs in clinical practice of IgG/IgA deamidated gliadin peptide antibodies (DGP) as a complement to IgA antibodies against tissue transglutaminase (tTG) for the diagnosis of pediatric celiac disease (CD). PATIENTS AND METHODS: All consecutive patients <18 years tested for tTG and/or DGP and who underwent duodenal biopsy because of suspected CD in Stockholm and Gothenburg, Sweden, 2008-2010 were included. Medical records were reviewed. RESULTS: Of 537 children who underwent duodenal biopsy, 278(52%) had CD. 71(13%) were <2 years and 13(4%) had IgA deficiency. Sensitivity and specificity for tTG was 94% and 86% respectively. Corresponding values for DGP was 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 <2 years with normal IgA, PPV was 96%(25/26) for tTG and 48%(24/50) for DGP. In 13 IgA deficient children 9 were DGP positive of which 4 had CD (PPV 44%). 8/278 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 &OV0556;399,520 or &OV0556;49,940 per case. CONCLUSION: For diagnosing CD, tTG is superior to DGP, even in children <2 years. Combining tTG and DGP does not provide a better trade off between number of missed cases of CD, number of unnecessary duodenal biopsies and cost than tTG alone