Cross-national comparison of inflammatory bowel disease burden in China, Japan, the United States, and India: An age-period-cohort analysis of GBD 2021

Background: Inflammatory bowel disease (IBD) has become widespread around the world. This study investigated trends in IBD incidence in China, Japan, India, and the United States (US) between 1990 and 2021. Methods: Data on IBD incidence, mortality, and the age-standardized incidence were obtained from the 2021 Global Burden of Disease public dataset, along with relative changes. An age-period-cohort model was employed to estimate net and local drifts and the relative risks associated with age, period, and cohort. Results: From 1990 to 2021, IBD incidence generally increased in China, Japan, and India, while the mortality decreased. In contrast, both IBD incidence and mortality in the US increased. Similar patterns of IBD incidence were observed in all countries in terms of age effects, with a trend of younger age at onset. However, differences in IBD incidence were noted in period and cohort effects. In China, IBD incidence rose among younger populations while declining slowly among older populations. In the US, the incidence increased overall, though slowly. Japan, on the other hand, had a relatively high IBD incidence among older populations. Overall, the net drifts observed in the four countries indicated an increase in IBD incidence from 1990 to 2021. Conclusion: This study reveals the epidemiological characteristics and challenges related to IBD in varying socioeconomic environments. This information is crucial for making informed decisions about policy, research, and investment. It will help create more effective strategies and allocate resources more effectively.