Incidence of inflammatory bowel disease by race and ethnicity in a population-based inception cohort from 1970 through 2010

Background: Although inflammatory bowel disease (IBD) has been more predominant in white populations, an increasing incidence of IBD in nonwhites has been reported. We sought to evaluate the incidence rates and temporal trends of IBD by race and ethnicity. Methods: The resources of the Rochester Epidemiologic Project were used to identify 814 county residents newly diagnosed with IBD from 1970 through 2010. Race was categorized into whites and nonwhites. Ethnicity was categorized into Hispanic and non-Hispanic. Incidence rates were estimated and adjusted for age and sex to the 2010 United States (US) population. Trends in incidence rates were evaluated by Poisson regression. Results: The adjusted annual incidence rate of IBD for whites was 21.6 cases per 100,000 person-years [95% confidence interval (CI), 20.0-23.1] and for nonwhites it was 13 per 100,000 (95% CI, 8.3-17.5). The incidence rates for whites and nonwhites increased by 39% and 134%, respectively, from 1970 through 2010. The adjusted annual incidence rate of IBD for Hispanics was 15 cases per 100,000 person-years (95% CI, 6.3-23.6) and for non-Hispanics was 20 per 100,000 (95% CI, 18.5-21.6). The incidence rate for Hispanics decreased by 56%, while the rate for non-Hispanics increased by 33%, from 1985 through 2010. In a Poisson regression, white race (p < 0.0001), a later year of diagnosis (p < 0.001), male sex (p < 0.001) and younger age (p = 0.009) were significantly associated with a higher incidence rate of IBD. Conclusions: There were significant racial and ethnic differences in the incidence and temporal trends of IBD over the last four decades in this US population-based cohort.