Global study maps the spread of IBD in Africa, Asia, and Latin America

Inflammatory bowel disease, which includes Crohn's disease and ulcerative colitis, has long been considered a modern condition of the industrialized West, with cases steadily increasing in North America and Europe throughout the 20^th century. New research conducted by an international consortium shows that IBD and related conditions are now spreading through developing regions in Africa, Asia, and Latin America as well.

The study, published in Nature, used data from more than 500 population-based studies covering more than 80 geographic regions to describe a pattern of four distinct stages IBD progresses through as it first appears in a region and spreads through the population. In describing these stages, the researchers hope to provide resources and guidance to local health care systems for coping with the growing burden of patients with IBD.

The research was conducted by the Global IBD Visualization of Epidemiology Studies in the 21st Century (GIVES 21) consortium, a group of international IBD and public health experts led by Gilaad G. Kaplan, MD, from the University of Calgary and Siew C. Ng, MBBS, PhD, from the Chinese University of Hong Kong. GIVES21 has built a large repository of IBD epidemiology data and offers open access to the complete dataset for researchers, clinicians, and patients worldwide through a web application.

"This has been a huge, collaborative effort to understand IBD around the globe," said GIVES21 team member David T. Rubin, MD, the Joseph B. Kirsner Professor of Medicine at the University of Chicago.

"Now that we recognize what's happening with IBD in emerging areas of the world, we can start focusing on being able to treat it in places where these conditions are new. We can also study it in these emerging areas so we might get new clues as to what's driving this so we can help prevent it," said Rubin, who is also the newly elected Chair of the International Organization for the study of IBD (IOIBD), which supported the new study.

Drawing on a century of data

The team drew on a century's worth of data about IBD compiled by GIVES21. They analyzed new diagnoses per year and total people living with IBD, and found that it is unfolding in four distinct, predictable stages:

1. Emergence: Currently seen in low-income countries, with both new and total cases remaining low.
2. Acceleration in Incidence: Marked by a rapid rise in new diagnoses as regions industrialize and lifestyles shift, though total cases remain limited.
3. Compounding Prevalence: With incidence stabilizing, prevalence soars-driven by low mortality and accumulating cases in younger populations.
4. Prevalence Equilibrium: Projected in several high-income regions by 2045, where new diagnoses balance disease related deaths, plateauing overall prevalence.

As a chronic inflammatory condition that is driven by immune system responses, IBD has been linked to so-called Western diets that are high in processed foods, animal products, and sugar while also low in fruits, vegetables, and whole grains. People in industrializing economies tend to adopt more elements of this diet, but that alone doesn't tell the full story; IBD is increasing in India, for example, which has a high proportion of people who are vegetarian.

Rubin said other factors may be contributing as well. Growing evidence points to the implications of how food is prepared and stored, as more researchers explore the effects of emulsifiers and microplastics in food on IBD. He also emphasizes that it's important to remember that IBD is really dozens of distinct different conditions caused by myriad genetic and environmental factors.

By understanding where you're studying the disease, what you're looking at, and which people are developing IBD, you can get different ideas of what might be driving it, which will help us separate out these different types of IBD and find the right ways to treat them."

David T. Rubin, MD, the Joseph B. Kirsner Professor of Medicine, University of Chicago

Applying lessons on a local scale

As Director of the Inflammatory Bowel Disease Center at UChicago, Rubin hopes to bring some of these same insights home on a smaller scale. He and his colleagues are planning to launch their own epidemiological study in Chicago to understand how different socioeconomic factors and access to care affect the largely Black and Latino patient populations on the south and southwest sides of the city who often have more severe versions of the disease.

"Even though we have one of the largest IBD centers in the world, there's a clear disparity in diagnosis and access to expert care just a mile from here," he said. "Taking something like this at a global level and getting down to the microcosm of the South Side of Chicago is incredibly important to find better ways to diagnose, treat, and eventually prevent IBD our own patients."