Irritable bowel syndrome (IBS) is a health problem that people sometimes assume to be primarily a Western phenomenon. This may be because until recently most of the popular discussion of IBS, and most of the scientific investigation of it as well, has taken place in Western countries. It is now clear from research conducted in all corners of the world, however, that IBS is a truly global human disorder occurring at high rates in every population of the planet. Three articles1,2,3 just published in the scientific literature provide new broad insights into IBS as a worldwide phenomenon.
The first of these papers is a meta-analysis (meaning summary analysis of all qualifying published studies) by Lovell and Ford in England1. It gives an enlightening planet-wide view of IBS, based on pooled findings from published studies on 80 different populations all over the world with a combined total of over a quarter of a million people suveyed.
There are certainly some problems with trying to draw overall conclusions from so many different studies conducted in numerous different countries. For example, how subjects were recruited varied greatly between studies. It is also unknown how comparable the translations and understandability of symptom questions were across the many different languages and cultures. Both of these variable may influence how IBS looks from country to country. The largest problem with coming to firm conclusions about the global manifestation of IBS, though, is almost certainly the fact that the diagnostic criteria used to detect it have evolved over the past decades. The oldest studies in Lovell and Ford’s summary analysis used the so-called Manning criteria (meeting 3 or more of those), which are the predecessors of the more recent Rome criteria, and those oldest criteria clearly inflate prevalence rates compared to Rome criteria. The Rome diagnostic criteria themselves have in turn also morphed over time – from Rome I to Rome II to Rome III, each version using questions that assess IBS somewhat differently and setting a bit different standards for what can be considered to be IBS. Fortunately, this single largest bias in estimating prevalence probably washes out to a large extent when all studies for each region are combined and averaged. In spite of such methodological variations that may limit precision in findings, some broad overall conclusions can definitely be drawn from this large body of studies summarized by Lovell and Ford about IBS as a world-wide disorder. These include the following:
1. IBS is very common in every part of the world. The overall prevalence in the 80 study populations was 11.2% of the general population, with no region of the world showing lower prevalence than 7% (see figure below).
2. There is great variability in prevalence rates between different regions of the world. The region with the highest rate of IBS, South America (21% IBS), has three times the rate of the region with the lowest prevalence, which is Southeast Asia with only 7% IBS rate. I created the below figure based on the pooled region data presented in Lovell and Ford’s article for easy at-a-glance comparison of IBS rates in different regions of the world. The reasons for the dramatic differences in IBS prevalence between parts of the world that are evident from this figure are unknown at the present time.
Figure: IBS prevalence in the regions of the world (based on pooled data from 81 studies reported by Lovell and Ford1):
3. IBS is clearly a female-predominant disorder, although it is common in both sexes. Overall, IBS is found world-wide in 14.0% of women and 8.9% of men. There are some countries like India, Pakistan and China where this female predominance is not as clearly seen. In contrast, the U.S. has even more striking sex difference, with 2 to 1 female/male ratio in community surveys and as high as 4 to 1 in specialty clinics (the latter amplified ratio almost certainly due to the fact that women are on average far more likely than men to go to doctors in the U.S.).
4. IBS is somewhat less common in older individuals. The prevalence across all these international studies was 11.0% for individuals in their 20s and 30s, 9.6% for those in their 40s, 7.8% in the 50s, and 7.3% for people age sixty and older.
The other two articles that have been very recently published on this topic are a consensus statement published by the World Gastroenterology Organisation Summit Task Force on IBS2, and a report on the 2012 joint Rome Foundation and World Gastroentrology expert meeting on global IBS2. These articles provide an overall picture generally consistent with the four main global characteristics of IBS listed above, but add some nuances and details. The former of these articles2 points out, for example, that studies on the effects of IBS on quality of life indicate that impact on people’s lives is similar and substantial in different parts of the world; that all over the world, care for individuals with IBS constitutes a large proportion of the workload of gastroenterologists; and that associations with psychosocial features such as anxiety, depression and abuse history, as well as high overlap with certain other gastrointestinal and non-GI medical conditions (such as functional dyspepsia, fibromyalgia and chronic pelvic pain), seem to characterize IBS all over the world. The latter article3 summarizes discussion among experts about cultural, linguistic and geographic differences in IBS assessment and care and the various obstacles that these factors pose to the study of the phenomenon of IBS across countries and world-wide.
What these three articles published within the past few months collectively demonstrate, is that IBS is a vast health problem for the human population in general and that GI experts from around the world are increasingly joining forces to understand the disorder on a global scale. If the prevalence of 11.2% world-wide is approximately correct, as calculated by Lovell and Ford1, it can be estimated that a staggering 578 million individuals 15 yeas and older are suffering from this disorder right now (given the current world population of about 7 billion people and 26.3% of that population being under age 154). Many of these IBS sufferers will have relatively mild symptoms. But even if only a minority of them are severely affected by tthe disorder, their numbers are so high that IBS is likely to have significant impact on societies everywhere. This is especially likely considering that most IBS patients live with family members or are in intimate relationships, and many are employed in settings where they work in close collaboration with co-workers. So apart from the substantial demand that so many people ill with IBS place on healthcare resources of different nations, the various functional impairments caused by the bowel symptoms are also likely to affect both IBS sufferers and multiple people in their most immediate social network, causing significant overall effects in lost work productivity and impairment in human well-being across the globe.
1: Lovell RM, Ford AC. Global prevalence of and risk factors for irritable bowel syndrome: a meta-analysis. Clin Gastroenterol Hepatol. 2012 Jul;10(7):712-721. PubMed PMID: 22426087.
2: Quigley EM et al. A global perspective on irritable bowel syndrome: a consensus statement of the World Gastroenterology Organisation Summit Task Force on irritable bowel syndrome. J Clin Gastroenterol. 2012
May-Jun;46(5):356-66. PubMed PMID: 22499071.
3: Sperber AD, Drossman DA, Quigley EM. The global perspective on irritable bowel syndrome: a rome foundation-world gastroenterology organisation symposium. Am J Gastroenterol. 2012 Nov;107(11):1602-9. PubMed PMID: 23160283.