Reliability of antitransglutaminase antibodies as predictors of gluten-free diet compliance in adult celiac disease.
OBJECTIVE
Strict lifelong compliance to a gluten-free diet (GFD) minimizes the long-term risk of mortality, especially from lymphoma, in adult celiac disease (CD). Although serum IgA antitransglutaminase (IgA-tTG-ab), like antiendomysium (IgA-EMA) antibodies, are sensitive and specific screening tests for untreated CD, their reliability as predictors of strict compliance to and dietary transgressions from a GFD is not precisely known. We aimed to address this question in consecutively treated adult celiacs.


METHODS
In a cross-sectional study, 95 non-IgA deficient adult (median age: 41 yr) celiacs on a GFD for at least 1 yr (median: 6 yr) were subjected to 1) a dietician-administered inquiry to pinpoint and quantify the number and levels of transgressions (classified as moderate or large, using as a cutoff value the median gluten amount ingested in the overall noncompliant patients of the series) over the previous 2 months, 2) a search for IgA-tTG-ab and -EMA, and 3) perendoscopic duodenal biopsies. The ability of both antibodies to discriminate celiacs with and without detected transgressions was described using receiver operating characteristic curves and quantified as to sensitivity and specificity, according to the level of transgressions.


RESULTS
Forty (42%) patients strictly adhered to a GFD, 55 (58%) had committed transgressions, classified as moderate (< or = 18 g of gluten/2 months; median number 6) in 27 and large (>18 g; median number 69) in 28. IgA-tTG-ab and -EMA specificity (proportion of correct recognition of strictly compliant celiacs) was 0.97 and 0.98, respectively, and sensitivity (proportion of correct recognition of overall, moderate, and large levels of transgressions) was 0.52, 0.31, and 0.77, and 0.62, 0.37, and 0.86, respectively. IgA-tTG-ab and -EMA titers were correlated (p < 0.001) to transgression levels (r = 0.560 and R = 0.631, respectively) and one to another (p < 0.001) in the whole patient population (r = 0.834, N = 84) as in the noncompliant (r = 0.915, N = 48) group. Specificity and sensitivity of IgA-tTG-ab and IgA-EMA for recognition of total villous atrophy in patients under a GFD were 0.90 and 0.91, and 0.60 and 0.73, respectively.


CONCLUSIONS
In adult CD patients on a GFD, IgA-tTG-ab are poor predictors of dietary transgressions. Their negativity is a falsely secure marker of strict diet compliance.
Vahedi
Kouroche
K
Gastroenterology and Nutritional Support Unit, Lariboisière University Hospital, Paris, France.
Mascart
Françoise
F
Mary
Jean Yves
JY
Laberenne
Jean Eric
JE
Bouhnik
Yoram
Y
Morin
Marie Christine
MC
Ocmant
Annick
A
Velly
Christine
C
Colombel
Jean Frédéric
JF
Matuchansky
Claude
C
D000293:Adolescent; D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000097:blood*; D002446:Celiac Disease / Q000178:diet therapy* / Q000276:immunology* / Q000473:pathology; D003430:Cross-Sectional Studies; D004032:Diet; D004384:Duodenoscopy; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D005983:Glutens; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood*; D007413:Intestinal Mucosa / Q000276:immunology / Q000473:pathology; D008297:Male; D008875:Middle Aged; D010349:Patient Compliance; D012372:ROC Curve; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D011503:Transglutaminases / Q000276:immunology*
D001323:Autoantibodies; D007070:Immunoglobulin A; D005983:Glutens; D011503:Transglutaminases