Inflammatory bowel disease (IBD) is a chronic inflammatory disease that causes inflammation in all or parts of the intestines. The two most common types of IBD are Crohn’s disease and ulcerative colitis. While both conditions can cause symptoms such as abdominal pain, cramping, diarrhea or weight loss, there are differences between them. In Crohn’s disease, the inflammation can occur anywhere along the digestive tract, from the mouth to the anus, but most often affects the large and small intestines. In ulcerative colitis, the inflammation is restricted to the large intestine (colon) and/or rectum and is characterized by tiny open sores, or ulcers, which develop on the lining of the colon. IBD can be diagnosed at any age but the majority of cases are diagnosed in adolescence or early adulthood. Though IBD can be treated to reduce inflammation and manage symptoms, there is currently no cure.
The global scope of IBD
Traditionally, IBD has been characterized as a disease of Caucasians of European descent living in industrialized societies. Recent studies have shown that IBD is not primarily an issue of ancestry or ethnicity. The rate of IBD differs between regions where the genetic background is similar. IBD afflicts individuals of all ethnic groups whose families have lived in the western world for many generations.
During the 20th century, the diagnosed rate of IBD cases has steadily increased in western world regions, such as North America, Europe, Australia and New Zealand and currently represents 0.5% of the general population of those areas. In the United States alone, over 1 million individuals are estimated to suffer from IBD. In Europe, it is estimated that 2.5 - 3 million people live with IBD. But rates vary by location. Europe has a higher rate of ulcerative colitis while Australia has a higher occurrence of Crohn’s disease. IBD is equally distributed in North America. At present, it is clear that the majority of patients with IBD live in the Western world.
Recent studies in Europe have shown the contrast between different regions. For example, the rate of IBD is high in Western Europe while it is low in countries adjacent to the Mediterranean and varies from low to high throughout Eastern Europe. An updated evaluation shows the rate of IBD in Eastern Europe (11 per 100,000) approached the incidence in Western Europe (14 per 100,000) and that patients in Eastern Europe experienced more complications at diagnosis.
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There is also some evidence that pediatric-onset of IBD is on the rise in the Western world. For example, rates of diagnosed IBD are significantly increasing in children under 10 years of age. When IBD begins at such an early age, the disease is more pervasive and serious when compared with adult onset. The recent trend in pediatric-onset IBD shows that affected individuals come from a wide range of different cultural backgrounds. For example, if a child from a low prevalence country, such as India, moves to a high-prevalence country, such as Canada, then their chance of developing IBD increases to that of Canada. Therefore, genetic risk does not explain the trend analysis over the past century.
While rates have plateaued in some of these western areas, developing countries that are relatively new to modern industry in Asia, South America and the Middle East are seeing a significant increase in diagnosed IBD cases. Until the middle of the 20th century, IBD was relatively rare in developing countries but since that time rates of IBD have steadily grown. Though the overall number of diagnosed cases of IBD in newly industrialized countries is significantly lower when compared to developed countries, IBD is increasing at a much higher rate than in Western world countries. And projections suggest a significant global increase of IBD in the next decade.
The emergence and increase of IBD
It is accurate to call IBD a modern disease because it has emerged alongside 20th century western culture advances in transportation, agriculture, manufacturing, urbanization and dietary habits. During this time period there have been dramatic shifts in how modern society functions. We’ve transitioned from a mostly rural setting to urban living; from a farming society to an industrial one and from a survival mentality to a consumeristic mindset. Along with these changes we’ve adopted lifestyle behaviors such as smoking, low-fiber diets, less physical activity and exposure to environmental toxins. Combine these changes with advancements in our economic and social environments, along with better healthcare access and delivery, and IBD emerges as a disease of affluence.
Several studies have established that IBD has now taken hold in newly industrialized countries and parallels the growth patterns of the western culture in the 20th century. Epidemiologic studies have consistently shown a rapid rise in the rates of ulcerative colitis and Crohn’s disease in countries that transition from developing to industrialized economies. As developing countries become westernized, IBD should become more prevalent.
The future global outlook
Several environmental risk factors associated with industrial societies are undeniably involved in the development and spread of IBD globally. Yet, is it unclear which risk factors play the greatest part in the ongoing development of IBD in western culture and the rapid emergence of IBD in newly industrialized countries. Advances in technology, better access to healthcare and disease surveillance will continue to improve the detection of IBD.
What seems more certain is that IBD is emerging as a global disease and appears to be in the rise. This increase will be accentuated by more young people being diagnosed with IBD and many older adults living longer with IBD. The combination of these age factors alone will exponentially expand the number of cases.
As more newly industrialized countries adopt Western world practices, newly industrialized countries with large populations (e.g. China and India, each with 1 billion residents) could eventually have more cases of IBD than western-oriented countries. This creates many challenges for the medical profession as increasing numbers of people with IBD will need care. The healthcare systems in both the western world and newly industrialized countries need to prepare for a dramatic increase in the number of patients with IBD over the next decade. During this time it is crucial that we also focus research on the interaction between genes, the environment and intestinal microbes to better understand the root cause(s) of IBD and stem the global burden of IBD.
Note: Many of the concepts summarized in this article are covered in more detail in Dr. Gil Kaplan’s Essay entitled “The Global Burden of IBD: From 2015 to 2025“,published on September 1, 2015 in Nature Reviews Gastroenterology and Hepatology. That essay sheds new light on the global burden of IBD, using history, epidemiology, and the current body of literature to paint the landscape of IBD in 2015 and to predict how IBD will evolve over the next decade. Dr. Kaplan can be seen discussing these concepts in his talk entitled: “Investigating the causes of a modern disease of modern times”. YouTube link: https://www.youtube.com/watch?v=YSG4jDPlD1c