Incidence and Clinical Outcomes of Inflammatory Bowel Disease in South Korea, 2011–2014: A Nationwide Population-Based Study

Background: The incidence of inflammatory bowel disease (IBD) is increasing in East Asia; however, population-based data from this region are lacking. Aim: We conducted a nationwide, population-based study to examine the incidence and disease course of IBD in South Korea. Methods: Using the National Health Insurance claims data, we collected data on patients diagnosed with IBD [10,049 with ulcerative colitis (UC) and 5595 with Crohn’s disease (CD)] from 2011 to 2014. Results: During the study period, the average annual incidence of UC was 5.0 per 10⁵, while that of CD was 2.8 per 10⁵. Among patients with UC, the cumulative rates of surgery 1 and 4 years after diagnosis were 1.0 and 2.0%; those among patients with CD were 9.0 and 13.9%, respectively. The 1- and 4-year cumulative rates of moderate- to high-dose corticosteroid use were, respectively, 26.6 and 45.2% among patients with UC, and 29.9 and 50.8% among those with CD. Similarly, the 1- and 4-year cumulative rates of immunomodulator use were 14.1 and 26.4% among patients with UC, and 58.3 and 76.1% among those with CD, respectively. With regard to biologic use, the 1- and 4-year cumulative rates were 3.0 and 9.0% among patients with UC, and 11.1 and 31.7% among those with CD, respectively. Conclusions: The recent incidence of IBD in South Korea has been the highest in East Asia. Patients who had been diagnosed recently with IBD showed lower rates of surgery and higher rates of immunomodulator and biologic use compared to those reported ever in South Korea.