Introduction Although worldwide and Scottish¹data has clearly shown a persistent rise in paediatric inflammatory bowel disease (PIBD), population-based trends in early-onset incident PIBD (i.e. diagnosed before their 10^thbirthday; Paris A1a) are lacking. We aimed to evaluate the incidence of PIBD A1a between 1981–2013 using a complete national cohort study.

Method National data from previously published incident cohorts of PIBD in Scotland during 1981–1995 and 2003–2008 were first examined; prospectively collected incident cases from 2009–2013 were also included. Patients were only included following thorough case-note review. As IBD-unclassified (IBDU) was not a recognised IBD type in the earlier cohorts, the classification of non-Crohn’s colitis (NCC; i.e. ulcerative colitis and IBDU combined) was introduced to allow comparisons. Incidence rates were calculated using publicly available population data and trends across cohorts calculated using Poisson regression.

Results 402 A1a PIBD patients were identified with a slight (53%) male preponderance; approximately 60% were Crohn’s disease (CD) with the remainder NCC. There was a steady increase in incident cases with 39 patients diagnosed between 1981–1985 and 134 between 2008–2013. The adjusted incidence of A1a PIBD rose from 1.2/100,000/yr (95% CI 0.8–1.6) (1981–1985) to 4.1/100,000/yr (95% CI 3.5–4.7) (2008–2013) (p < 0.001); the incidence rate remainded stable in the most recent epoch (2008–2013). The incidence of the 0–5 yr group rose from 0.7/100,000/yr (1981–1985) to 2.0/100,000/yr (2008–2013) (p = 0.017) compared to an incidence rise of 2.0/100,000/yr (1981–1985) to 7.2/100,000/yr (2008–2013) (p < 0.001) in the 6–9 yr group. The incident rate ratio between the first and last epochs were 2.9 (95% CI 1.5–6.4) and 3.6 (95% CI 2.3–5.8) in the 0–5 yr and the 6–9 yr age groups respectively. There were no significant sex differences across any group and both the CD and NCC groups showed similar trends.

Conclusion Using population-based Scottish data from the previous four decades we have shown that early-onset PIBD (A1a) has shown a significant rise in incidence, with three-fold increases seen in both the very-early-onset (0–5 yr) and 6–9 yr age groups. However, incidence rates seem to have stabilised in the last decade, despite a sustained rise in overall PIBD.¹Further examination of these young patients may provide clues to IBD aetiopathogenesis.

Disclosure of interest None Declared.

References

1. Henderson P, et al.J Crohns Colitis. 2015;9(S1):S2

2. Benchimol, et al. Gastroenterology 2014;147(4):803–813