Despite the rising incidence and prevalence of inflammatory bowel disease (IBD) in Asian populations, data regarding clinical characteristics of patients in Asia based on age at diagnosis are relatively sparse. The aim of this study was to compare clinical characteristics based on the age at diagnosis according to the Montreal Classification in Korean IBD patients.

We recruited consecutive patients with IBD at two tertiary hospitals and retrospectively reviewed their medical information. Patients were divided into three groups according to their age at diagnosis: youth (<17 years), young adult (17-40 years), and middle-old (>40 years). The main clinical characteristics for comparison were the achievement of a remission state at the last follow-up visit, cumulative rate of surgery, and cumulative use of immunomodulators and tumor necrosis factor-α (TNFα) blockers during the follow-up period.

In total, 346 IBD patients were included (Crohn's disease [CD] 146 and ulcerative colitis 200; 36 youth, 202 young adult, and 113 middle-old). The middle-old group with CD was characterized by a predominance of uncomplicated behavior ( P =0.013) and a lower frequency of perianal disease ( P =0.009). The middle-old group was associated more with a less aggressive disease course than the younger group, as shown by more frequent remission ( P =0.004), being less likely to undergo surgery ( P <0.001), and lower cumulative use of immunomodulators and TNFα blockers ( P <0.001).

Age at diagnosis according to the Montreal Classification is an important prognostic factor for Korean IBD patients.