BACKGROUND AND AIMS: Few studies have assessed the contemporary patterns of disease activity in patients with inflammatory bowel disease (IBD). We aimed to describe the disease patterns and their long-term outcomes.

METHODS: All Danish individuals with IBD between 1995 and 2018 were identified using information about IBD-related hospitalizations, surgeries, and redeemed prescriptions. The disease activity patterns for 5- and 10-year periods were assessed.

RESULTS: In incident patients with Crohn's disease (CD), severe disease activity occurred in the year of diagnosis in 80% of patients; for ulcerative colitis (UC) this figure was 75%, in addition to 3.4% of UC patients who underwent a colectomy within the first year. After 20 years of disease, the proportion of CD and UC patients in remission increased to 89% and 72%, respectively. The proportion of prevalent patients in remission each year was stable, despite the introduction of biological therapies. A decreasing activity pattern was the most common in both CD and UC patients (both 45%). The distribution of the disease activity patterns was observed to be stable over time. A quiescent disease pattern was accompanied by a significantly higher risk of intestinal cancer (HR: 3.37, 95%CI: 1.23-9.19) for CD patients, according to a Cox proportional hazards model. In UC patients, increasing disease activity (HR: 0.67, 95%CI: 0.31-1.48) was associated with an increased risk of intestinal cancer.

CONCLUSIONS: We reported the distribution of disease patterns among IBD patients. Patients with quiescent CD, as well as UC patients with chronic continuous or increasing activity, were at increased risk of developing intestinal cancer.