Irritable Bowel Syndrome and Inflammatory Bowel Disease: Is There an Overlap?

Irritable Bowel Syndrome (IBS) is a common and sometimes disabling syndrome which has been reported to affect up to 10–15% of adults in North America (1) and Western Europe (2,3); inflammatory bowel disease (IBD), though less common, affecting approximately 0.5% of the Canadian population (4), is not rare. It should come as no surprise, therefore, that these entities should, on occasion, coincide or coexist, albeit by happenstance. Recent descriptions of immune activation and even subtle mucosal inflammation in IBS have raised the possibility of a more fundamental relationship between IBS and IBD. This review will address two issues: firstly, at a pathophsyiological level, the relationships between IBS and IBD and, secondly, in a clinical context, the interpretation of IBS-type symptoms among IBD patients in apparent remission. IS IBS PART OF THE SPECTRUM OF IBD? In past decades, when IBS sufferers were commonly employed as “controls” in IBD studies, IBS was regarded as a mere nuisance to be occasionally tolerated by the hoi polloi of that rarefied community, the IBD confraternity. The very suggestion that IBD, a disorder populated by innumerable T-cell subsets and complexities of mucosal immunology and human genetics comprehensible only to that elite cadre of practitioners and clinical researchers possessed of the intellectual prowess to enter this field, had anything in common with IBS, a messy, vague and marginal entity, would be treated with the scorn it deserved and dismissed with derision. How things have changed? As yet another T cell subset failed to deliver, the litany of cytokines and chemokines possibly linked to IBD stretched even further into a darkening horizon and yet another gene mutation disappointed, the gaze of the IBD-ologist began to wander and, reluctantly, and secretly (as no self-respecting IBD aficionado could admit in public that he or she was dabbling in the dark arts of IBS) began to rest on IBS. Meanwhile, though handicapped by an inferior intellect and an ignorance INFLAMMATORY BOWEL DISEASE: A PRACTICAL APPROACH, SERIES #66