Thirty-year Trend in Inflammatory Bowel Disease on Jeju Island, South Korea.

Background/aims: Inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), is increasing in South Korea. On the other hand, there are no reports of the incidence and prevalence of IBD specific to Jeju Island, prompting the necessity of this study.
Methods: In this retrospective design, the medical records of 453 patients diagnosed with IBD at Jeju National University Hospital from January 1990 to December 2019 were analyzed.
Results: Of the 453 IBD subjects (165 CD, 288 UC) included, the UC: CD ratio was 1.75:1. The incidence of IBD increased continuously from 0.19/10 ⁵ in 1990 to 6.39/10 ⁵ in 2017 and after that decreased to 4.92/10 ⁵ in 2019. The male:female ratio was 2.24:1 for CD and 1.29:1 for UC. In the CD subjects, the disease activity included remission (33.3%), mild (25.5%), moderate (30.9%), and severe (6.1%). In UC subjects, the disease activity included remission (24.0%), mild (35.4%), moderate (28.8%), and severe (6.2%). According to the Montreal classification, the cases were as follows: CD: terminal ileum (22.4%), colon (9.7%), ileocolon (66.1%), and upper gastrointestinal involvement (27.3%), and perianal fistula/abscess was present in 43.6% of subjects before or at diagnosis: UC: proctitis (43.4%), left-sided colitis (29.1%), and pancolitis (23.3%) at diagnosis.
Conclusions: The incidence of IBD on Jeju Island has increased steadily for approximately 30 years but has exhibited a decline since 2017. Therefore, the incidence of IBD in Jeju is believed to have plateaued. Further study will be needed for clarification.