Su2026 PPI Use and Small Intestinal Bacterial Overgrowth Detected on Lactulose Breath Testing: Results of a Prospective Cross Sectional Study Among U.S. Veterans With Irritable Bowel Syndrome

Background/Aims: Proton Pump Inhibitors (PPIs) have been proposed to be the missing link in the controversy surrounding Small Intestinal Bacterial Overgrowth (SIBO) and Irritable Bowel Syndrome (IBS). Recent studies examining the relationship between PPIs and SIBO have been limited by retrospective analysis and failure to control for confounding factors such as somatization which may be common to both PPI use and SIBO. Consequently, the aims of this prospective cross sectional study were: 1) To calculate adjusted Odds Ratios (ORs) for hydrogen (H2) and methane (CH4) SIBO based upon PPI use 2) To determine the impact of PPI use on Lactulose Breath Testing (LBT) parameters. Methods: 149 nondiabetic veterans (67 PPI users, 82 non-users, 82% male, mean age 45) meeting Rome III IBS criteria undergoing LBT were recruited. Data on IBS subtype and severity (IBS Severity Scoring System), bloating, depression/anxiety (Hospital Anxiety Depression Score) and somatization (Psychosomatic Symptom Checklist) were obtained by questionnaire. Use of PPIs, fiber, laxatives, probiotics, H2-Blockers, anti-cholinergics, diagnoses of GERD and BMI were obtained from the medical record. LBT's were defined as positive using different criteria: 1) Two H2 Peaks (Increase .20 ppm over the baseline by 90 min with a single peak occurring at least 15 min prior to the second peak with a trough after the first peak of . 5ppm) 2) Increase in H2 by . 20 ppm by 90 min. 3) Any CH4 . 5 ppm 4) Rise in CH4 by. 20 ppm by 90 min. Adjusting for confounding factors using logistic regression, adjusted ORs for PPI use and SIBO were calculated. LBT parameters including baseline H2 and CH4, amplitude of rise to first H2 peak (P1), and time to P1 were compared between PPI and non-PPI groups using Wilcoxon rank sum and t-tests. Results: The prevalence of H2-SIBO using Two H2 Peak criteria was 36.9% in PPI vs. 17.9% in Non-PPI groups (p=0.01). Adjusted OR for PPI Use and Two Peak H2-SIBO was 4.3 (95% CI 1.4-12.9, p=0.01). PPI use of . 180 days was found to be associated with Two Peak H2-SIBO with OR 3.2 (95% CI 1.2-8.9, p=0.02). ORs for PPI use and SIBO were not statistically significant using the other H2 or CH4 criteria (Table). Among LBT parameters, there was a trend towards a shorter time to P1 in the PPI group (Fig 1). However, a statistically significant difference was found in time to P1 when comparing PPI use of .180 days vs. , 180 days (58.7 vs. 75.7 min, p=0.02) (Fig 1). Comparisons between PPI vs. Non-PPI groups did not find differences in baseline H2 (0 vs. 0 ppm, p=0.45), CH4 (1 vs.1.2 ppm, p=0.70) or amplitude to P1 (50 vs. 45 ppm, p=0.55). Conclusions: PPI use is associated with an increased prevalence of H2-SIBO on LBT but only when using the Two H2 Peak criteria. This may be caused by an earlier rise in H2 in the proximal small bowel seen with prolonged PPI use. (Table) Adjusted Odds Ratios for PPI Use and SIBO Using Different H2 and CH4 Criteria