Background and aims We aimed to determine the predictors and risk for death among persons with either Crohn's disease (CD) or UC compared with the general population.

Methods We used the population-based University of Manitoba IBD Epidemiology Database to calculate HRs and their 95% CIs for cases relative to controls using stratified multivariable Cox proportional hazards regression models, controlling for socioeconomic status and comorbidities.

Results There were 10 788 prevalent cases of CD and UC and 101 860 matched controls. The HR for all-cause mortality in prevalent CD cases was 1.26 (95% CI 1.16 to 1.38) and in prevalent UC cases was 1.04 (95% CI 0.96 to 1.12). Compared with matched controls, CD cases were more likely to die of colorectal cancer, non-Hodgkin's lymphoma, digestive diseases, pulmonary embolism and sepsis and UC cases were more likely to die from colorectal cancer, digestive diseases and respiratory diseases. For incident cases, there were significant effects on mortality by socioeconomic status, comorbidity score and surgery. The greatest risk for death in both CD and UC was within the first 30 days following GI surgery. The first year from diagnosis was associated with increased risk of death in both CD and UC, but persisted after the 1st year only in CD.

Conclusions There is a significantly increased risk of mortality in CD compared with controls while in UC an increased risk for death was only evident in the first year from diagnosis. Surgery poses an increased risk for death in both CD and UC lasting up to 1 year.