Specific phenotypes may drive an increased incidence of pediatric inflammatory bowel disease in South-Eastern Norway.

OBJECTIVES

Pediatric inflammatory bowel disease (PIBD) incidence has increased in recent decades but may be stabilizing, prompting exploration of incidence changes, disease distribution, and severity.

METHODS

From 2017 to 2019, patients under 18 years with PIBD symptoms were recruited from nine hospitals in South-Eastern Norway for Inflammatory Bowel Disease in South-Eastern Norway III (IBSEN III), a population-based inception cohort study. The primary outcome was a diagnosis of any PIBD subtype as defined by revised Porto criteria. Paris classification system defined disease phenotypes, and descriptions of covariates were gathered from patients in IBSEN III.

RESULTS

We identified 324 PIBD patients, with 216 consenting to the IBSEN III study. The crude incidence rate was 17.8 per 100,000 person-years (PY) (95% confidence interval [CI]: 15.9-19.8). Crohn's disease (CD) was found in 118 patients (54.6%); 48% had ileocolonic distribution, 40% had upper gastrointestinal disease, and 12.8% had perianal disease. Complications (stricturing and/or penetrating) were noted in 18%. Ulcerative colitis (UC) was diagnosed in 78 patients (36.1%), predominantly pancolitis (41%), with 30% having proctitis. One in five suffered severe disease. IBD unclassified was found in 20 patients (9.3%). PIBD incidence in those under 16 was 13.6/100,000 PY, up from 4.7 in the IBSEN study 27 years ago. Terminal ileitis (11%-23%) and proctitis (14%-25%) rose from IBSEN (1990-1993) to IBSEN III, while stricturing/penetrating disease changed insignificantly (17%-16%).

CONCLUSIONS

The incidence of PIBD has risen in South-Eastern Norway, with increased cases of terminal ileitis in CD, unchanged stricturing/penetrating disease, and increased proctitis in UC compared to the original IBSEN study.

CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02727959.