Introduction

The incidence of paediatric inflammatory bowel disease (IBD), encompassing ulcerative colitis (UC) and Crohn’s disease (CD), is increasing worldwide. A recent systematic review revealed the existence of a knowledge gap concerning the global epidemiology of paediatric IBD, highlighting the need for further research within the field; especially population-based cohorts, as many previous studies fall short concerning cohort size, study period, selection bias or level of detail on disease phenotypes¹. IBD diagnosis during childhood has been associated with a more severe disease course², and patients often require life-long preventative medical treatment and surgical interventions^3,4. Thus, a thorough understanding of paediatric IBD and its development over time is essential. In Denmark, we have a unique opportunity to identify unselected population cohorts, allowing scrutiny of medical files and detailed descriptions of patient cohorts. In the North Denmark Region, where clinical data on adult patients with IBD have been recorded in a clinical database for decades, a recent effort to identify all paediatric patients in the region through four decades has been made.

Aims & Methods

The aim of the study was to 1) present a comprehensive cohort of all patients diagnosed with IBD within the North Denmark region before the age of 18 between 1978-2020, 2) describe their age, gender, IBD subtype, family history, and clinical presentation at diagnosis, and 3) examine how these features had changed over the past four decades.
We identified all children diagnosed with IBD in the North Denmark Region (589,936 inhabitants in 2020) during 1978-2020 to establish the Paediatric NorDIBD cohort (pNorDIBD). Patients were identified from the Danish National Patient Registry and the North Denmark clinical IBD registry GASTROBIO. Diagnoses were assessed by a clinical gastroenterologist and the medical files of each patient were manually scrutinized for information about disease presentation and full disease course.

Results

A total of 249 children with UC and 220 children with CD were included. The incidence rate of paediatric IBD increased 182% in four decades. Median age at diagnosis was 15.4 years for UC and CD, and it had increased over time. In UC, the proportion of proctitis, distal colitis and pancolitis were similar at diagnosis (34.5%, 25.7% and 32.1%). Most children with CD were diagnosed with either ileocolonic or colonic CD (34.1% and 40.5%). The proportion of pancolitis, ileocolonic CD and penetrating CD had increased notably in four decades. The rise in ileocolonic and penetrating CD was statistically significant (p=0.047 and p=0.028). IBD in a first degree relative was registered in 22.4% of cases, and these children were significantly younger at diagnosis (p=0.004).

Conclusion

With the pNorDIBD cohort, a population-based cohort of paediatric IBD, we provide a unique description of paediatric IBD in a high-incidence country through four decades. We found extent of disease at diagnosis in the pNorDIBD cohort to differ from other recent studies of paediatric IBD^5,6, with reassuring data suggesting less extensive disease than previously reported, though with temporal data suggesting a hitherto unexplored trend toward more severe disease at diagnosis. The pNorDIBD cohort aims to be a valuable resource in future research regarding paediatric IBD. Detailed information about each patient’s disease course provides several opportunities for further studies, aiming to assist in mending part of the current knowledge gap concerning the global epidemiology of paediatric IBD.

References

1. Kuenzig ME, Fung SG, Marderfeld L, et al. Twenty-first Century Trends in the Global Epidemiology of Pediatric-Onset Inflammatory Bowel Disease: Systematic Review. Gastroenterology. 2022;162(4):1147-1159.e4. doi:10.1053/J.GASTRO.2021.12.282
2. Pigneur B, Seksik P, Viola S, et al. Natural history of Crohn's disease: comparison between childhood- and adult-onset disease. Inflamm Bowel Dis. 2010;16(6):953-961. doi:10.1002/ibd.21152
3. Nordenvall C, Rosvall O, Bottai M, et al. Surgical Treatment in Childhood-onset Inflammatory Bowel Disease-A Nationwide Register-based Study of 4695 Incident Patients in Sweden 2002-2014. J Crohns Colitis. 2018;12(2):157-166. doi:10.1093/ECCO-JCC/JJX132
4. Adamiak T, Walkiewicz-Jedrzejczak D, Fish D, et al. Incidence, clinical characteristics, and natural history of pediatric IBD in Wisconsin: a population-based epidemiological study. Inflamm Bowel Dis. 2013;19(6):1218-1223. doi:10.1097/MIB.0B013E318280B13E
5. Arai K, Kunisaki R, Kakuta F, et al. Phenotypic characteristics of pediatric inflammatory bowel disease in Japan: results from a multicenter registry. Intest Res. 2020;18(4):412-420. doi:10.5217/IR.2019.00130
6. Malmborg P, Grahnquist L, Ideström M, et al. Presentation and progression of childhood-onset inflammatory bowel disease in Northern Stockholm County. Inflamm Bowel Dis. 2015;21(5):1098-1108. doi:10.1097/MIB.0000000000000356

Disclosure

TJ reports consultancy for Ferring and Pfizer. LL reports speaker fee from Takeda and advisory board for Tillotts and Abbvie. All other authors have none to declare.