Comparative Effectiveness of Urine vs. Stool Gluten Immunogenic Peptides Testing for Monitoring Gluten Intake in...

Coeliac disease (CD) is a chronic immune-mediated enteropathy triggered by gluten ingestion in genetically predisposed individuals carrying HLA-DQ2 or HLA-DQ8 haplotypes, characterized by small intestinal mucosal damage and systemic manifestations. This systematic review and meta-analysis aimed to compare the effectiveness of urine versus stool GIPS testing for monitoring gluten intake in coeliac patients, providing evidence-based recommendations for clinical practice. A comprehensive literature search was conducted in databases like PubMed and Embase. Studies evaluating urine or stool GIPS testing in coeliac patients were included, focusing on sensitivity, specificity, and patient adherence. The meta-analysis included six studies with a total of 572 participants. The stool GIPS testing demonstrated a pooled sensitivity of 85.1% (95% CI: 79.0-89.9%) and a specificity of 92.5% (95% CI: 88.3-95.6%), making it highly reliable for detecting gluten exposure and ruling out false positives. It also achieved an AUC of 0.9853, indicating excellent diagnostic performance. In contrast, the urine GIPS testing showed a pooled sensitivity of 55.4% (95% CI: 49.6-61.2%) and a specificity of 73.0% (95% CI: 67.4-78.1%), with an AUC of 0.7898. The heterogeneity across the studies was significant (I² > 80%), driven by variations in the population characteristics, sample handling, and testing protocols. These findings emphasize the need for standardized methodologies to enhance the reliability and comparability of results.