Background: Evidence suggests a role for small intestinal bacterial overgrowth (SIBO) in IBS. Recently, the question has arisen whether the lactulose breath test (LBT) is abnormal in IBS subjects due to overlapping GERD and proton-pump inhibitor (PPI) usage.
Aim: The aim of this study was to compare the prevalence of an abnormal LBT in IBS patients either receiving or not receiving PPI therapy.
Methods: Consecutive Rome I positive IBS patients referred for LBT completed a questionnaire regarding their symptoms and medication use. All subjects then underwent an LBT. The prevalence of abnormal breath test results and hydrogen production were compared based on PPI usage.
Results: Of a total of 555 (429 female) subjects, 106 (19.1%) subjects reported current PPI use. Among those on PPI, 46.2% had a positive LBT. This was not different from the 56.3% positive LBT in non-PPI subjects (OR = 0.67, CI = 0.436-1.017, P = 0.06). No differences in hydrogen parameter were seen with PPI. The average amplitude of rise (first peak) in PPI users was 28.0 +/- 35.3 ppm from baseline; in non-PPI users it was 27.5 +/- 29.1 ppm (P = 0.89). The average rise in the second peak in PPI users was 48.5 +/- 43.8 ppm from baseline; in non-PPI users, it was 49.3 +/- 37.6 ppm (P = 0.87). The time to first peak in PPI users was 56.4 +/- 23.0 min; in non-PPI users, it was 58.2 +/- 26.1 min (P = 0.58). However, among subjects receiving PPI only 7.5% had methane detection on LBT, which is significantly different from the 15.4% of subjects not taking PPI.
Conclusion: PPI therapy does not effect hydrogen production on lactulose breath tests in IBS patients. However, there may be an effect on methane.