Introduction It has always been assumed that irritable bowel syndrome (IBS) is more common in women. However, there has been no systematic review and meta-analysis that has synthesised data from all available studies to estimate prevalence of IBS according to gender. There has also been no study that has investigated whether the presumed higher prevalence in women varies according to the way in which IBS is defined, and whether it holds true for all IBS subtypes.
Methods MEDLINE, EMBASE, and EMBASE Classic were searched through October 2011 for cross-sectional surveys reporting the prevalence of IBS. A recursive search was also conducted. There were no language restrictions. Eligible studies were population-based, recruited ≥50 adult (≥15 years) subjects, and were required to define IBS via the Manning or Rome I, II or III criteria. Eligibility assessment and data extraction were conducted independently in a double-blind fashion by two investigators, with discrepancies resolved by consensus. Data were extracted and pooled, with a random effects model, to estimate prevalence of IBS according to gender. An OR, with a 95% CI, was used to compare the female to male prevalence of IBS, as well as the prevalence of constipation-predominant (IBS-C), diarrhoea-predominant (IBS-D), and mixed-type (IBS-M) among women and men meeting criteria for IBS.
Results The search yielded 20 146 results, of which 390 studies appeared relevant and were retrieved for further assessment. There were 80 separate population-based studies that reported the prevalence of IBS according to the above criteria. Of these, 55 reported IBS prevalence according to gender, with a pooled prevalence in women of 14.0% (95% CI 11.0% to 16.0%) compared with 8.9% (95% CI 7.3% to 10.5%) in men (OR 1.67; 95% CI 1.53 to 1.82). Prevalence was consistently higher in women when all definitions of IBS were considered: the OR for women compared to men was 1.55 (95% CI 1.35 to 1.78) with the Manning criteria, 1.99 (95% CI 1.76 to 2.25) with Rome I, 1.40 (95% CI 1.24 to 1.59) with Rome II, and 1.81 (95% CI 1.36 to 2.39) with Rome III. Nine studies, with 63 827 participants, also reported the breakdown of IBS according to subtype. Prevalence of IBS-C was significantly higher in women with IBS compared with men (OR 2.38; 95% CI 1.45 to 3.92), IBS-D was less common in women with IBS compared with men (OR 0.45; 95% CI 0.32 to 0.65), while prevalence of IBS-M was not significantly different according to gender (OR 1.07; 95% CI 0.84 to 1.38).
Conclusion Prevalence of IBS was modestly increased in women. This observation remained stable according to the various diagnostic criteria used. However, among individuals with IBS, women were more likely to have IBS-C than men, and less likely to have IBS-D. These data suggest that gender may influence IBS subtype.
Competing interests None declared.