OP027 The rising incidence of early-onset paediatric inflammatory bowel disease (Paris A1a) in Scotland since 1981: a national, population-based, cohort study
P. Henderson*1, F.L. Cameron1, F. Jagger2, R. Hansen3, H. Drummond4, E. Reynish5, S. Loganathan2, R.K. Russell3, J. Satsangi4, D.C. Wilson1
1University of Edinburgh, Child Life and Health, Edinburgh, United Kingdom, 2Royal Aberdeen Children's Hospital, Department of Paediatric Gastroenterology, Aberdeen, United Kingdom, 3Royal Hospital for Sick Children, Paediatric Gastroenterology, Glasgow, United Kingdom, 4University of Edinburgh, Gastrointestinal Unit, Centre for Genomic and Experimental Medicine, Edinburgh, United Kingdom, 5University of Stirling, School of Applied Social Science, Stirling, United Kingdom
Although worldwide data has clearly shown the persistent rise in paediatric inflammatory bowel disease (PIBD), trends in the incidence of early-onset PIBD (i.e. diagnosed before their 10th birthday; Paris A1a) are not yet clear. Recent administrative data suggests that A1a PIBD has shown a dramatic rise in recent years  , however robust population-based incidence data are lacking. We aimed to evaluate the incidence of PIBD A1a disease in Scotland across four decades using a complete national cohort study.
National data from previously published incident cases of PIBD in Scotland during the periods 1981-1995 and 2003-2008 were examined to determine those diagnosed less than 10yrs of age; prospectively collected incident cases from 2009-2013 were also included. A1a cases were divided into two sub-groups for further analysis (0-5yrs and 6-9yrs at diagnosis). Incidence rates were calculated using publicly available population data from the Scottish government and trends across cohorts calculated using Poisson regression analysis.
A total of 402 A1a PIBD patients were identified during the study periods. There was a steady increase in incident cases across epochs: 39 (1981-1985), 54 (1986-1990), 63 (1991-1995), 112 (2003-2007) and 134 (2008-2013) cases respectively. The crude incidence of A1a PIBD rose from 1.2/100,000/yr (1981-1985) to 4.0/100,000/yr (2008-2013) (p<0.001). The crude incidence of those diagnosed at 0-5yrs of age rose from 0.7/100,000/yr (1981-1985) to 2.0/100,000/yr (2008-2013) (p=0.017) compared to an incidence of 2.0/100,000/yr (1981-1985) to 7.2/100,000/yr (2008-2013) (p<0.001) for those diagnosed at 6-9yrs of age. 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) for the 0-5yr and the 6-9yr age group respectively, demonstrating a three-fold increase in both groups across the study period.
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 (0-5yr) and 6-9yr age groups. Further examination of these young children, especially with regard to epigenetics and environmental exposures may provide clues to IBD aetiopathogenesis.
 Benchimol, et al., (2014), Incidence, Outcomes, and Health Services Burden of Very Early Onset Inflammatory Bowel Disease, Gastroenterology, 147(4):803-813