Testing for fecal gluten immunogenic peptides: a useful tool to evaluate compliance with gluten-free diet by celiacs

Abstract

Background Although experts agree that strict dietary compliance is fundamental for the health of celiac patients, there are no evidence-based recommendations on the best way to assess dietary compliance. Detection of gluten immunogenic peptides (GIPs) in feces was recently proposed as an effective method of assessing the dietary compliance of celiac patients. Methods Fifty-five consecutive celiac patients (27 adults and 28 children, age 6-72 years), who had been on a gluten-free diet for at least 2 years, were enrolled. All patients were evaluated clinically for symptoms, physical parameters and laboratory parameters. Dietary compliance was assessed with the Biagi questionnaire and serum anti-tissue transglutaminase (tTG) IgA antibodies were measured. GIPs were determined by immunoenzymatic assay on an automated Chorus analyzer (DIESSE Diagnostica Senese), after extraction of fecal samples by the method developed by DIESSE. Results Eight patients tested positive for GIPs (GIPs+); 71.4% of GIP-positive patients were asymptomatic; tTG antibodies were detected in 3/8 GIP+ patients. The Biagi score was significantly associated with fecal positivity for GIPs (P=0.02). However, according to the Biagi score, 57.1% of GIP+ patients followed the diet strictly and 5.4% of GIP- subjects did not comply with the diet or made substantial mistakes. Conclusions Assay of fecal GIPs identified more patients who did not comply with the diet than did the Biagi questionnaire, evaluation of symptoms or anti-tTG antibodies. Detection of fecal GIPs offers a direct, objective, quantitative assessment of even occasional exposure to gluten and is confirmed as a practical way to check dietary compliance.

Determination of gluten immunogenic peptides for the management of the treatment adherence of celiac disease: A systematic review

“…Some children, particularly the older ones, were reported to have a propensity for GFD non-compliance, and 46% of non-adherent participants had at least two GIP-positive stools during follow-up[ 40 ]. Similar data were reported by other groups[ 22 , 44 ]. Patients with higher levels of gluten exposure exhibited prolonged ascension of anti-tTG antibodies ( P < 0.05) than those with GIP-negative results.…”

“…In contrast, Costa et al [ 41 ] reported that most adult patients with gluten transgressions determined via GIP detection were asymptomatic, although the difference was not statistically significant due to the low number of cases enrolled. Similar data were published by Porcelli et al [ 44 ] wherein the rate of asymptomatic patients with GIP-positive results was 71.4%.…”

“…Of those patients with good adherence using CDAT ( n = 66), three had GIP-positive results. Porcelli et al [ 44 ] also found a significant association between strict diet adherence estimated by the Biagi score and fecal GIP detection. According to the Biagi score, 94.6% of GIP-negative patients exhibited good adherence.…”

“…In a considerable number of studies, biopsies and recurrent excretion of GIP indicated that serological tests, symptoms, and dietary questionnaires were not sufficient indicators of GFD adherence[ 9 , 23 , 29 - 31 ]. However, anti-tTG antibodies and clinical dietary assessment have been recently suggested as complementary tools in the evaluation of GFD adherence[ 44 , 45 ]. In this context, Porcelli et al [ 44 ] proposed the use of the Biagi score in combination with fecal GIP tests using a binary logistic regression model.…”

Poor Sensitivity of Fecal Gluten Immunogenic Peptides and Serum Antibodies to Detect Duodenal Mucosal Damage in Celiac Disease Monitoring

“…Therefore, it would be advisable to combine GIP with other tools. A recent study suggested combining fecal GIPs with a CDAT questionnaire as the best option for monitoring dietary compliance in celiac patients [ 42 ].…”