LAUSR

BACKGROUND Inflammatory bowel disease (IBD) prevalence is rising globally however indigenous groups are underrepresented. Waikato, New Zealand is a large region with a high proportion of Māori patients. In Canterbury in 2006, 1% of IBD patients were Māori. We investigated the incidence and prevalence of IBD in Waikato over 10 years. METHODS This was a retrospective cohort study assessing the incidence and prevalence of IBD between 2009 and 2019. The search strategy included pathology, radiology, ProVation, ICD-10 coding and private clinics, using the key words: Crohn's, Crohn, ileitis, colitis, ulcerative, inflammatory bowel disease, IBD. Collected data included current age and at diagnosis, gender, ethnicity and IBD subtype. RESULTS The IBD point prevalence on 31st December 2019 was 375.6/100000 compared to 293.6/100000 in 2010, increasing by 27.9%. The annualized incidence was static from 21.5/100000 in 2010 to 17.5/100000 in 2019. 53.3% of patients were female. 54.2% had Ulcerative Colitis (UC), 43.8% had Crohn's Disease (CD) and 2.0% indeterminate colitis. 60 (3.7%) patients identified as Māori. In Non-Māori patients, the average age at diagnosis was 36.2 years, compared to 33.0 years in Māori patients (p=0.11). In Māori patients, 53.3% had UC and 45.0% had CD. 35% of Māori patients lived 50km or more from base hospital, compared to 41% of non-Māori patients (p=0.33) CONCLUSION: The IBD prevalence has increased substantially, however the incidence has remained static. Māori IBD rates are higher than previously reported, in keeping with international Indigenous trends. Māori patients were diagnosed at a similar age as Non-Māori patients, with similar disease subtypes. This article is protected by copyright. All rights reserved.