The epidemiology of Crohn’s and Colitis in New Zealand: a data linkage study.

Crohn’s disease and ulcerative colitis are Inflammatory Bowel Diseases (IBD) affecting approximately 20,000 New Zealanders, a number expected to double by 2026. New Zealand has no national IBD registry, which means timely and accurate data on New Zealand’s IBD epidemic is limited, hampering accurate projections for optimal health service planning and delivery. We will use longitudinal hospitalisation and pharmaceutical data available within Statistic New Zealand’s Integrated Data Infrastructure (IDI) to identify IBD-cases nationwide using an algorithm. The feasibility study involves the development, refinement and validation of the IBD identifying algorithm, by comparing the algorithm-identified-IBD-cases with clinically well-characterised patients identified by collaborating gastroenterologists. If successful, we will use the algorithm to establish a nationwide longitudinal IBD study, which will be the first to provide national data to reliably quantify the burden of IBD expressed as morbidity, comorbidity and health care cost. This will guide improvements in IBD care.