What is Inflammatory Bowel Disease (IBD)?

The term Inflammatory Bowel Disease (IBD) generally refers to both Crohn’s Disease (CD) and Ulcerative Colitis (UC), which, as the name suggests are both chronic diseases involving inflammation of the gastrointestinal tract. Additionally around 5-10% of patients present with a colitis (inflammation of the colon or large bowel) that is difficult to diagnose as either UC or CD and can be described under the microscope as ‘indeterminate’. Though there is much ongoing research we do not know the cause of these two conditions and subsequently cannot offer a ‘cure’ of either condition. As well as being bowel conditions, there can be associated inflammation of the skin, eyes and joints and there are also some associations with liver conditions. The causes of both diseases are multifactorial with genetic and environmental factors likely to play a role. The last decade or so has seen a great increase in our understanding of these diseases and the treatments which are effective, and increasingly the need for a multidisciplinary approach in their management. Both diseases have the potential for considerable social embarrassment and can have a profound effect on quality of life. In this article I will discuss both UC and CD in some detail with a focus on the treatments we can offer and also hope to answer frequently asked questions about the diseases and their management.



Prevalence and Incidence



As a rough estimate there are somewhere between 180,000 and 200,000 people in the UK with IBD, with an average sized UK hospital having 45-50 new cases per year with around 500 under follow-up (1). Of these around 60-80,000 will have CD and 120,000 have UC. The number of newly diagnosed cases is relatively stable although there is some evidence that the incidence of Crohn’s may be increasing. The incidence of CD is around 5-10 per 100,000 per year with a prevalence of 50-100 per 100,000. This equates to around 1 in 1000 of the population. For UC the incidence is 10-20 per 100,000 per year with a prevalence of 100-200 per 100,000 which equates to about 1 in 500 of the population. Recent studies have demonstrated that there is a genetic component to both diseases. For UC, having a first degree relative increases the risk of developing the disease by 10-15 fold which equates roughly to a 5% risk. This does mean however that there is a 95% of not developing the disease and this should be emphasised. There is a similar 10 fold risk in CD, though this may be even higher in particular ethnic groups such as the Ashkenazi Jewish.



Ulcerative Colitis



Ulcerative Colitis is a chronic disease of inflammation of the mucosa (the skin lining the large bowel) of the colon. Generally speaking the inflammation is continuous and starts in the rectum, extending proximally into the colon to varying degrees (figure 1). Like CD, UC most commonly presents in younger years with a peak incidence between 10 and 40yrs. However, at least 15% of cases will present in the over 60.



Any cause of inflammation of the colon, especially infection, can cause diarrhoea and occasionally blood. Ulcerative colitis however will generally present with a chronic history of bloody diarrhoea which has not settled and this should always prompt investigation. People may sometimes find that their symptoms have been intermittent and occasionally the first attack is severe and requires hospitalisation.



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