Researchers with the University of Calgary and the Chinese University of Hong Kong (CUHK) led an international collaboration that found inflammatory bowel disease (IBD) progresses through four predictable epidemiological stages as it spreads globally. Published in Nature, the study forecasts a major rise in IBD prevalence in Canada by 2045. Researchers say pinpointing where each region sits on the trajectory gives health-care systems a clear roadmap for anticipating and managing IBD today and in the decades to follow.
"Our analysis draws on a century worth of historical epidemiologic data. The findings enable health authorities to prepare for IBD's growing burden and tailor interventions—whether clinical, policy driven, or preventive," says Dr. Gilaad Kaplan, MD, professor at UCalgary's Cumming School of Medicine and principal investigator on the study.
The Global IBD Visualization of Epidemiology Studies in the 21st Century (GIVES-21) consortium collected incidence (new diagnosis made each year) and prevalence (number of people living with the disease) data from more than 500 epidemiological studies conducted across 80 regions over the past century. Using these data, the team developed a machine learning algorithm and predictive modeling to classify countries into four distinct epidemiological stages of IBD evolution: emergence, acceleration in incidence, compounding prevalence, and prevalence equilibrium.
"Our GIVES-21 consortia is conducting epidemiologic surveillance studies in low- and middle-income countries as the disease is evolving in these regions," says Dr. Siew Ng, FRCP, PhD, professor at CUHK's Faculty of Medicine, and co-principal investigator on the study. "We are seeing a paradigm shift of IBD accelerating in region like Asia, and we must build the clinical infrastructure and workforce needed to manage this complex and costly disease."
IBD, comprising Crohn's disease (CD) and ulcerative colitis (UC), refers to chronic conditions that cause inflammation in the gastrointestinal tract. Onset often occurs in early life with the peak onset between 20 and 40 years of age and can cause lifelong symptoms.
Historically, IBD first emerged in the 19th century in early industrialised Western regions of North America, Europe and Oceania. Over the past two decades, however, IBD appeared in newly industrialised and developing regions across Asia, Latin America and Africa. The combination of rising incidence in newly industrialized countries and steadily increasing prevalence in early industrialized Western countries has made IBD a global health concern.
Based on the findings published in Nature Kaplan describes the stages of IBD throughout of the world,
"Developing regions in Africa, Asia, and Latin America in Stage 1 (emergence) transition to Stage 2 (acceleration in incidence) following economic growth, industrialization, urbanization, and changes in lifestyle and diet," says Kaplan.
"Countries in North America, Europe, and Oceania are in Stage 3 (compounding prevalence). They are seeing a growing number of people living with IBD, including an increasing proportion of seniors. These regions face a dual challenge: managing new cases in young adults while also supporting older patients with more complex health needs."
Kaplan adds prevalence of IBD will continue to rise as people live longer with the disease. However, he says as the IBD population ages, the rate of growth is expected to slow—moving toward Stage 4 (prevalence equilibrium), where new diagnoses are gradually balanced by age-related deaths.
The four epidemiological stages of IBD offer a powerful case study for understanding the global rise of chronic inflammatory diseases shaped by industrialization and modern living.
The first authors on the paper are Dr. Lindsay Hracs, BA '09, MA '11, PhD '21 and Dr. Joseph W. Windsor MA '12, PhD '17, members of the Kaplan lab.
