title: Use of deamidated gliadin peptide antibodies to monitor diet compliance in childhood celiac disease.
abstract: OBJECTIVE
  The aim of this study was to evaluate performance of serum antibodies against deamidated gliadin peptides (a-DGPs) in detecting compliance with gluten-free diet (GFD) in children with celiac disease (CD).
  
  
  METHODS
  Serum samples were collected the same day of endoscopy in 95 children with CD and 106 controls. We preliminarily calculated the cutoff of a-DGP immunoglobulin A (IgA) and a-DGP IgA+G in our population by receiver operating characteristic (ROC) curves. Of 95 children with CD, 28 were studied during the first year after GFD introduction, with interview and serum collection every 3 months. In addition, serum samples were collected in 106 children with CD on GFD for more than 1 year (range 1-14). In both groups of children with CD on GFD, we compared a-DGP IgA and IgA+G performance in monitoring compliance with GFD with anti-tissue transglutaminase antibodies (anti-tTG) IgA and anti-gliadin antibody (AGA) IgA.
  
  
  RESULTS
  The cutoff resulted in 13.1 arbitrary units (AU) for a-DGP IgA (sensitivity 87.4, 95% confidence interval [CI] 79%-92%, specificity 97.2, 95% CI 92%-99%) and 16.5 for a-DGP IgA+G (sensitivity 94.7, 95% CI 88%-98%, specificity 89.6, 95% CI 84%-95%). In the first year of GFD, at 6 to 8 months prevalence of positive a-DGPs was significantly higher in partially versus strictly compliant children, and at 9 to 12 months only prevalence of positive a-DGP IgA+G remained significantly higher. Moreover, at 9 to 12 months sensitivity to detect transgressions to GFD was 44% for a-DGP IgA and 100% for a-DGP IgA+G (P = 0.03). In the 106 children on GFD for more than 1 year, sensitivity to detect transgressions to GFD was 60% for a-DGP IgA and 76% for a-DGP IgA+G. Anti-tTG IgA and AGA IgA sensitivity was much lower (24% and 4%, respectively). The 4 tests showed comparable high specificity.
  
  
  CONCLUSIONS
  Both a-DGPs showed higher sensitivity than anti-tTG IgA and AGA IgA in monitoring compliance with GFD, but a-DGP IgA+G seemed to perform better. a-DGPs did not outperform anti-tTG IgA for CD screening.
authors.affiliation: Department of Pediatrics, Università del Piemonte Orientale, Novara, Italy.
authors.forename: Alice
authors.initials: A
authors.lastname: Monzani
authors.forename: Anna
authors.initials: A
authors.lastname: Rapa
authors.forename: Paola
authors.initials: P
authors.lastname: Fonio
authors.forename: Eleonora
authors.initials: E
authors.lastname: Tognato
authors.forename: Laura
authors.initials: L
authors.lastname: Panigati
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Oderda
mesh_terms: D000293:Adolescent; D000906:Antibodies / Q000032:analysis*; D002446:Celiac Disease / Q000178:diet therapy* / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D055050:Diet, Gluten-Free; D005903:Gliadin / Q000737:chemistry / Q000276:immunology*; D005983:Glutens / Q000008:administration & dosage / Q000009:adverse effects; D006801:Humans; D007070:Immunoglobulin A / Q000032:analysis; D007074:Immunoglobulin G / Q000032:analysis; D007223:Infant; D008297:Male; D010349:Patient Compliance; D010446:Peptide Fragments / Q000737:chemistry / Q000276:immunology*; D012680:Sensitivity and Specificity; D012698:Serologic Tests; D011503:Transglutaminases / Q000276:immunology
chemical_list: D000906:Antibodies; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D010446:Peptide Fragments; D005983:Glutens; D005903:Gliadin; D011503:Transglutaminases