Kaplan GG. Nature Reviews Gastroenterology & Hepatology. 2025;22:708-720. https://doi.org/10.1038/s41575-025-01097-1
Background & Rationale
Inflammatory bowel disease (IBD) has evolved from a sporadic Western condition to a global disease. Accurate prevalence forecasting enables health systems to prepare for resource allocation and workforce planning. The author proposes IBD progresses through four epidemiological stages: emergence (stage 1), acceleration in incidence (stage 2), compounding prevalence (stage 3) and prevalence equilibrium (stage 4). Understanding these transitions enables mathematical modelling of future disease burden, providing lead time for health systems to adapt infrastructure and prioritise prevention strategies for challenges between 2025 and 2045.
Study Design
This perspective paper synthesised epidemiological data from over 500 population-based studies (1920–2024) across more than 80 global regions. A machine learning classifier categorised regions into stages 1, 2 or 3 with 95% accuracy. Two forecasting methods were employed: autoregressive integrated moving average (ARIMA) models for short-term projections (approximately 10 years) and partial differential equations (PDEs) for long-term projections to 2045. PDE models incorporated age-specific and time-specific incidence rates, differential mortality and migration patterns. Scenario analyses explored variations in incidence trends and mortality rates.
Patient Population
Analysis included population-based data representing diverse global populations. Early industrialised countries (North America, Europe, Oceania) were predominantly in stage 3. Newly industrialised Asian and Latin American countries were transitioning from stage 1 to stage 2. Africa remained mostly in stage 1. The USA shifted to stage 2 in the 1950s and reached stage 3 in the 1970s; Japan transitioned to stage 2 in the 1990s; China in the 2010s; Malaysia in the 2020s. Projections anticipated global population reaching 9.44 billion by 2045.
Key Findings
Machine learning established coalescing ranges per 100,000 population: stage 1 (incidence 0.2–1.2, prevalence 1.1–10.4), stage 2 (incidence 3.3–10.6, prevalence 31.2–100.5) and stage 3 (incidence 18.1–34.1, prevalence 362.9–660.1). In 2025, early industrialised countries occupy stage 3, with prevalence approaching 1%. Canada showed 0.85% prevalence, USA approximately 0.7%. ARIMA models validated against Canadian data showed high accuracy.
Canadian PDE modelling predicted prevalence reaching 1.05% by 2043 at prevalence equilibrium (stage 4). Denmark demonstrated higher projected prevalence: 1.19% (2025) rising to 1.59% (2043). Scenario analyses showed sensitivity to incidence trends: 2% annual decline could reduce Canadian prevalence below 1% by 2045, whilst 2% increase could elevate Danish prevalence to 1.76% by 2043.
Ulcerative colitis to Crohn’s disease ratios narrowed from 3.2:1 (stage 1) to 1.5:1 (stage 3). Paediatric-onset IBD incidence rose in stage 3 countries whilst adult-onset declined. Newly industrialised Asian and Latin American countries will likely transition from stage 2 to stage 3 over two decades. Despite potentially lower prevalence, substantial population sizes will result in absolute case numbers exceeding North America and Europe by 2045.
Discussion
The framework explains how IBD transitions through predictable epidemiological stages driven by industrialisation, urbanisation and westernisation. Healthcare system preparedness is critical. Ageing IBD populations in stage 3 countries require different care models. Stage 2 regions face disease burden in working-age adults, creating substantial costs. Prevention strategies targeting environmental risk factors (smoking cessation, breastfeeding, judicious antibiotic use, healthy diet) could reduce incidence. Pre-disease biomarkers can identify high-risk individuals years before diagnosis. Healthcare innovations essential for managing increasing prevalence include multidisciplinary teams, telemedicine, point-of-care ultrasonography and biosimilars. Achieving deep remission could reduce the prevalent population requiring active management. Model limitations included uncertainty over longer horizons, regional heterogeneity, surveillance quality variations and potential disruption from unforeseen events.
Authors’ Conclusions
By 2025, IBD is firmly established globally, with every country positioned within the first three epidemiological stages. Over two decades, most countries will progress to stage 2 or 3, with some early industrialised nations potentially achieving stage 4. Combining ARIMA with PDE modelling enables plausible age-specific prevalence forecasts to 2045. Forecasting accuracy depends on epidemiological data quality. Regional variations create heterogeneity in incidence patterns. Even modest annual incidence changes meaningfully influence prevalence estimates. The global IBD community must prioritise prevention strategies whilst innovating healthcare delivery models to ensure equitable, accessible and cost-effective care by 2045.
Reference
Kaplan GG. The global burden of inflammatory bowel disease: from 2025 to 2045. Nat Rev Gastroenterol Hepatol. 2025;22:708-720. doi:10.1038/s41575-025-01097-1
This Scientific Publication Summary is an objective summary of the published trial for personal and educational use. It does not constitute clinical advice, endorsement of the intervention, or a recommendation to alter clinical practice.