W1000 Characterization of Norovirus-Associated Travelers' Diarrhea

Abstract

Recent studies suggest an association between detectable methane during breath testing and constipation. These studies have also demonstrated a correlation between the degree of methane and severity of constipation and improved constipation after antibiotics. This study aims to conduct a systematic review and meta-analysis to examine the evidence supporting an association between methane and constipation. Methods: Articles were searched in Pubmed, Medline, Ovid Journals, and Cumulative Index for nursing and allied health literature from 1950 to November 2009. Search terms included methane, breath test, constipation, motility, transit, and irritable bowel syndrome. Studies in the final analysis needed to demonstrate the prevalence of methane in a population and comparison to the presence or absence of constipation as a symptom. As part of the review, studies that also measured intestinal transit in methane and non-methane subjects were examined. To accomplish the analysis, two reviewers independently searched and extracted data. Pooled odds ratios and corresponding 95% CI were estimated using a random effects model. Results: The initial search terms generated 705 reference articles. From these, 44 relevant articles were fully reviewed with 9 studies meeting inclusion criteria for the primary meta-analysis. Among these 9 studies, 1277 subjects were examined by breath testing (including N=319 methane producers and N=958 methane non-producers). Seven of nine studies involved IBS patients only, and one study involved children. The remaining study examined non-IBS functional constipation. Pooling all 9 studies, there was a significant association between methane on breath test and constipation (OR=3.51, CI=2.00-6.16). When only adults were considered, methane was still significantly associated with constipation (OR=3.47, CI=1.84-6.54). Similar results were seen when examining only subjects with IBS (OR=3.60, CI=1.61-8.06) For all 9 studies, heterogeneity was moderate and Harbord's modified test suggested no significant publication bias (P=0.887). In addition, the systematic review identified 9 papers examining intestinal transit. While studies could not be combined for meta-analysis due to markedly different techniques (bowel frequency, orocecal and whole gut transit time), all 9 studies demonstrated that methane was associated with slow intestinal transit. Conclusion: This meta-analysis demonstrates that methane is significantly related to constipation in both IBS and functional constipation. This lends further support to the role of gut bacteria and their products in functional bowel disease and may lead to new directed therapies for constipation.