Never underestimate inflammatory bowel disease: High prevalence rates and confirmation of high incidence rates in Australia

Background and Aims: Regional variations in inflammatory bowel disease (IBD) rates have been observed. Limited epidemiological data are available from Australasia. IBD prevalence rates have never been assessed in an Australian population-based setting. In addition, there are few historical IBD incidence data to allow assessment of rate changes. The aims were to calculate Australia's first population-based IBD prevalence rates, to reassess local IBD incidence rates, and to establish a population-based inception cohort. Methods: An observational, prospective population-based epidemiological study was performed to assess IBD prevalence and incidence rates from July 2010 to June 2011 in a geographically defined Australian population (Barwon, Victoria). Results: There were 1011 prevalent IBD cases identified, representing a crude point prevalence rate of 344.6 per 100 000 on June 30, 2011. Crohn's disease was the most common prevalent subtype. Seventy-one incident cases of IBD were identified, with a crude incidence rate of 24.2 per 100 000. Crohn's disease was again more common. Local incidence rates have not changed between 2007 and the present study. All incident cases were successfully incorporated into an inception cohort. Conclusion: The burden of IBD in our local region is high. Demographic similarities allow these results to be applied to the broader Australian community. We propose that the number of existing and new cases each year in Australia has been previously underestimated. These revised figures will be important when planning the provision of health resources for these patients in the future and when assessing need for research funding priorities.