Comparison of abdominal bloating severity between Irritable Bowel Syndrome patients with high and low levels of breath hydrogen excretion in a lactulose breath test.

BACKGROUND There is growing evidence that gut flora plays a role in the development of Irritable Bowel Syndrome (IBS). Abdominal bloating is a common symptom in these patients and the severity of this symptom could be related to the variations in their fermentative profiles, obtained by measuring the levels of breath hydrogen excretion after lactulose ingestion. AIMS Our objective was to determine the difference in abdominal bloating severity between IBS patients with high vs low levels of breath hydrogen excretion after lactulose administration. METHODS Lactulose breath tests were carried out on IBS patients in our institution between July 2009 and August 2010. Patients were requested to fill out a validated questionnaire to assess the severity of their symptoms. Abdominal bloating severity score was compared among patients with high and low breath hydrogen levels. RESULTS A total of 234 patients were enrolled. There was a statistically significant difference in the abdominal bloating severity score between groups: 7.0 (5.7-8.0) vs 6.5 (5.0-7.5), p=0.001. The comparison among IBS patients with constipation (IBS-C) in both groups also showed a statistically significant difference: 7.5 (6.0-8.5) vs 5.8 (3.5-7.2), p=0.0051. CONCLUSIONS Those patients with a low level of breath hydrogen excretion after lactulose ingestion presented with significantly greater abdominal bloating than those with a high level of breath hydrogen excretion.