Tu1425 Relationship of HLA-DQ Genotype With Small Bowel and Colonic Transit and Permeability, and Small Bowel Inflammation in Patients With Irritable Bowel Syndrome With Diarrhea (IBS-D)

Abstract

Background: Colorectal hypersensitivity is considered an important pathophysiological mechanism in irritable bowel syndrome (IBS). Meal intake exaggerates colorectal sensitivity in IBS and patients often report a meal-related symptom aggravation. Aim: To evaluate the additive information of a test meal during rectal sensitivity testing in IBS regarding the association with other rectal sensorimotor function parameters and gastrointestinal (GI) and psychological symptoms.Methods:We included 221 patients with IBS (age 39±13 (mean±SD) years; 160 females). All subjects underwent a rectal barostat study with two isobaric phasic distension sequences, one before and one 60 min after a liquid meal (800 kcal; 60% lipids). Sensory thresholds were determined during the distensions. Cut-off levels for rectal hypersensitivity (<31 mmHg before, and <26 mmHg after a test meal) were based on data from healthy controls. We also assessed static (V/P) and dynamic compliance (ΔV/ΔP) during the distensions. Patients were characterized regarding GI symptoms (GSRS-IBS), anxiety and depression (HAD) and GI specific anxiety (VSI). Results: In the fasting state, 42% were hypersensitive without gender difference and after the test meal 34% were hypersensitive with a female predominance (p=0.03). Of those with hypersensitivity after meal intake, 20% had normal sensitivity in the fasting state. Hypersensitive patients were younger (p=0.04 before, p<0.001 after meal) and had higher dynamic compliance compared to normosensitive patients both before and after the test meal. Patients with fasting hypersensitivity reported more severe abdominal pain, diarrhea and satiety, as well as higher levels of GI-specific and general anxiety. Patients with hypersensitivity after the test meal reported more severe pain, diarrhea, satiety, bloating and GI specific anxiety (Table 1). Meal hypersensitive patients had more severe bloating (p<0.05) and lower dynamic compliance (p<0.05) than patients with fasting hypersensitivity only. Factors bivariately associated with rectal sensitivity were entered into multiple linear regression analyses, and only GSRS scores for pain were found to be independently associated with rectal sensitivity both in the fasting state (β=-0.19, p= 0.04) and after the test meal (β=-0.19, p=0.04), while diarrhea was independently associated with fasting rectal sensitivity only (β=-0.20, p=0.01). Conclusion: Rectal sensitivity seems to contribute to GI symptom severity in IBS, independently of anxiety and depression levels. Adding a test meal during the procedure provides some additional information to rectal sensitivity testing, even though the majority of relevant information regarding pathophysiology and relevance for symptom generation can be obtained with rectal sensitivity testing in the fasting state only. Table 1. Between group differences (mean (SD))