The association between inflammatory bowel disease and all-cause and cause-specific mortality in the UK Biobank

Purpose: Inflammatory bowel disease (IBD) has a rising global prevalence. However, the understanding of its impact on mortality remains inconsistent so we explored the association between IBD and all-cause and cause-specific mortality. Methods: This study included 502,369 participants from the UK Biobank, a large, population-based, prospective cohort study with mortality data through 2022. IBD was defined by baseline self-report or from primary care or hospital admission data. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause and cause-specific mortality in multivariable Cox proportional hazards regression models. Results: A total of 5799 (1.2%) participants had a history of IBD at baseline. After a median follow-up of 13.7 years, 44,499 deaths occurred. Having IBD was associated with an increased risk of death from all causes (HR = 1.16, 95% CI = 1.07–1.24) and cancer (HR = 1.16, 95% CI = 1.05–1.30), particularly colorectal cancer (CRC) (HR = 1.56, 95% CI = 1.17–2.09). We observed elevated breast cancer mortality rates for individuals with Crohn's disease, and increased CRC mortality rates for individuals with ulcerative colitis. In stratified analyses of IBD and all-cause mortality, mortality risk differed by individuals’ duration of IBD, age at IBD diagnosis, body mass index (BMI) (P_{Heterogeneity} = 0.03) and smoking status (P_{Heterogeneity} = 0.01). Positive associations between IBD and all-cause mortality were detected in individuals diagnosed with IBD for 10 years or longer, those diagnosed before the age of 50, all BMI subgroups except obese individuals, and in never or current, but not former smokers. Conclusions: We found that having IBD was associated with increased risks of mortality from all causes, all cancers, and CRC. This underscores the importance of enhanced patient management strategies and targeted prevention efforts in individuals with IBD.