Colon to Rectum
Nature. 2025;642(8067):458-466
Global evolution of inflammatory bowel disease across epidemiologic stages
During the twentieth century, inflammatory bowel disease (IBD) was considered a disease of early industrialized regions in North America, Europe and Oceania. At the turn of the twenty-first century, IBD incidence increased in newly industrialized and emerging regions in Africa, Asia and Latin America, while the prevalence in early industrialized regions continued to grow steadily. Changes in the incidence and prevalence denote the evolution of IBD across four epidemiologic stages: stage 1 (emergence), characterized by low incidence and prevalence; stage 2 (acceleration in incidence), marked by rapidly rising incidence and low prevalence; and stage 3 (compounding prevalence), where the incidence decelerates, plateaus or declines while the prevalence steadily increases. A fourth stage (prevalence equilibrium) has been proposed in which the prevalence slope plateaus due to demographic shifts in an ageing IBD population, but it has not yet been evidenced. To date, these stages have remained theoretical, lacking specific numerical indicators to define transition points. Here, using real-world data from 522 population-based studies encompassing 82 global regions and spanning more than a century (1920–2024), the authors show spatiotemporal transitions across stages 1–3 and model stage 4 progression. Understanding the evolution of IBD across epidemiologic stages enables healthcare systems to better anticipate the future worldwide burden of IBD.
DOI: 10.1038/s41586-025-08940-0
Prof. Dr. Peter Hasselblatt
Deputy Director Department of Internal Medicine II, University Medical Center Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany
Epidemiology of inflammatory bowel disease: What does the future hold?
The incidence of inflammatory bowel disease (IBD) increases significantly in parallel with industrialization, a development that can be described in 4 epidemiological phases. Phase 1 is characterized by the sporadic occurrence of IBD, with low incidence and prevalence rates. As industrialization progresses, Western lifestyle and dietary patterns become more common, phase 2 emerges, marked by a significant rise in incidence while prevalence remains low. After reaching a plateau, incidence starts to decline in phase 3, whereas prevalence continues to increase due to the chronic nature of the disease. Phase 4, which remains hypothetical, may eventually be characterized by a decrease in prevalence within an aging IBD population as age-related mortality rises.
In a study published in Nature, Hracs et al. evaluated this epidemiological framework using data from 522 population-based studies conducted across 82 countries between 1920 and 2024. Their analysis confirmed marked regional variability in IBD epidemiology. For example, in Scandinavian countries, incidence increased approximately 5-fold between 1970 and 2010, followed by stabilization of incidence and a continuous rise in prevalence.
These epidemiological patterns, first observed in Western industrialized countries, now appear to be emerging in developing and newly industrialized countries, where IBD incidence is currently on the rise. Interestingly, some regions reported a markedly elevated incidence. Further studies of these populations may yield important insights into potential genetic risk factors contributing to disease development. Several environmental determinants such as Western diet, level of health care, economic development, and urbanization correlated closely with the occurrence of the respective epidemiological phases 1 to 3.
Since phase 4 has not yet been observed in any country, the authors used their dataset to mathematically model transitions from phase 3 to phase 4. Once incidence stabilizes in an aging population, prevalence is expected to decline due to increased mortality. In several countries such as Canada, Scotland and Denmark, IBD prevalence has risen more sharply among older individuals than in younger cohorts. According to the authors’ calculations, however, an equilibrium in prevalence is unlikely to occur before 2040. In the long term, we must therefore prepare ourselves for a significant increase in the number of individuals affected by IBD, with prevalence projected to rise to between 1.0% and 1.7%.
These calculations are crucial for anticipating the future global burden of IBD and to better allocate health care resources. At the same time, this worrying increase in IBD prevalence underlines the need to improve early identification of individuals at risk, enhance preventive measures, and to develop more effective and affordable therapies.