Disease Activity Patterns of Paediatric Inflammatory Bowel Disease – A Danish Nationwide Cohort Study (1996-2018)

Background and Aims

Inflammatory bowel diseases (IBD) are heterogeneous in the frequency and severity of their flare-ups. We aimed to describe disease activity patterns in a Danish nationwide paediatric IBD cohort.

Methods

Paediatric patients (<18 years at diagnosis) with Crohn’s disease (pCD) or ulcerative colitis (pUC) in the study period from 1996 to 2018 were identified in national registers. Disease activity (severe, moderate-to-mild, remission) was assessed at diagnosis according to medications prescribed, hospitalisations and surgeries.

Results

1,965 pCD and 1,838 pUC incident patients were included in the cohort. At diagnosis, severe disease activity was found in 87%/80% of pCD/pUC in addition to 6.1% of pUC patients had undergone a colectomy during the first year after diagnosis. Five years after diagnosis, the annual proportions of pCD/pUC with no disease activity were 70%/72%, and 10 years after diagnosis the proportions were 61%/64%. Colectomy was required in 6.1%, 12% and 16% of pUC patients after 1, 5 and 10 years.

No improvement of disease activity was seen in the proportion of prevalent pCD (N=2,515) and pUC (N=2,428) in the study period 2000-2018 concomitant with the introduction of biological treatment. Albeit decreasing disease activity was the most common pattern in both pCD and pUC (43% and 47%), respectively.

Conclusions

pIBD was characterised by a high proportion of patients with severe activity at diagnosis, followed by an improvement after five and ten years of follow-up. Notably, the proportion of patients with no disease activity was unchanged when biological treatment was introduced and the number of colectomies in pUC remained high.