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An international consortium led by The Chinese University of Hong Kong (CUHK)’s Faculty of Medicine (CU Medicine) and the University of Calgary in Canada has conducted a global epidemiological study on Inflammatory Bowel Disease (IBD). It found that this chronic gut condition follows a four-stage epidemiological evolution across different regions of the world. Analysing data from more than 500 epidemiological studies across 80 regions in the past century, the team generated a machine-learning model for classification of stages which enables health-care systems to prepare for the growing burden on healthcare arising from the prevalence of IBD. Results of the study have been published in the leading scientific journal Nature.   

Growing IBD population seen worldwide

IBD, comprising Crohn’s disease (CD) and ulcerative colitis (UC), refers to a group of chronic conditions that cause ulceration and inflammation in the gut. The onset of the disease typically occurs in early life with the peak onset between 20 and 40 years of age, and with a range of lifelong symptoms such as rectal bleeding, abdominal pain, mucus in stools, diarrhoea, weight loss, fever and extra-intestinal inflammation of other organs, including the eyes, skin and joints. Treatment for IBD usually involves drug therapy or, in severe cases, surgery.

The disease was first recognised in regions of the West, including North America, Europe and Oceania, that were early to industrialise in the 19^th century, and gradually emerged in newly industrialised and developing regions in Asia, Latin America and Africa at the turn of the 21^st century. IBD has emerged as a threat to global public health, with increasing incidence in developing countries and rising prevalence in developed countries.

Epidemiological model informs trend of IBD burden for the next 20 years

The Global IBD Visualization of Epidemiology Studies in the 21st Century (GIVES‑21) consortium, led by Professor Gilaad Kaplan of University of Calgary and Professor Siew Ng of CU Medicine, synthesised data from 522 population-based studies across 82 geographical regions over the past century. They observed differences in IBD incidence and prevalence across various geographical areas over the past century suggest that epidemiological patterns shift through time.

To further explore the trends and characterise the epidemiology of IBD independent of geography and time, researchers developed a machine-learning model that classifies regions by epidemiologic stage, maps spatiotemporal transitions across stages and models a theoretical prevalence stage for the next two decades. They also demonstrated a stage where IBD prevalence reaches equilibrium. (Please refer to Table 1 in appendix for details.)

Professor Gilaad Kaplan, Professor of Medicine at the Cumming School of Medicine, the University of Calgary, said: “Our analysis, drawing on a century’s worth of historical epidemiologic data, enables health authorities to tailor interventions – whether clinical, policy driven or preventive.”

Incidence rapidly rising in China and Malaysia while Japan and South Korea seeing an acceleration in prevalence

Study data showed epidemiological stages vary among regions in Asia. Japan and South Korea, which underwent rapid industrialisation in the latter half of the 20^th century, have reported prevalence exceeding 0.1%, placing them on the brink of transitioning towards stage 3. In contrast, nations like China and Malaysia, which industrialised later, entered stage 2 more recently.

Dr Joyce Mak, Honorary Clinical Associate Professor in the Department of Medicine and Therapeutics at CU Medicine, said: “Today, we stand at a critical juncture as we address the alarming rise in IBD in newly industrialised countries such as China and Malaysia. This increase is not just a statistic; it represents the health and well-being of millions of people. As these nations embrace rapid industrialisation and urbanisation, we must prioritise public health initiatives, enhance awareness, and invest in research to understand underlying causes of this disease.”

Professor Siew Ng, Croucher Professor in Medical Sciences at CU Medicine, Director of the Microbiota I-Center (MagIC)and New Cornerstone Investigator, said: “Our GIVES‑21 consortium is conducting epidemiologic surveillance studies in low- and middle-income countries, as the disease is evolving in these regions. We are seeing a paradigm shift of IBD accelerating in these regions and we will need to prepare our clinical infrastructure and personnel to manage this complex and costly disease. We are planning research to focus on preventive strategies targeting the gut microbiome, diet and environmental exposures to reduce disease incidence.”

This study was supported by The Leona M. and Harry B. Helmsley Charitable Trust, the International Organization for the study of IBD (IOIBD), and contributions from over 30 international partners.