The inexorable increase of biologic exposure in paediatric inflammatory bowel disease: a Scottish, population‐based, longitudinal study

BACKGROUND: The use of biologics in paediatric‐onset inflammatory bowel disease (PIBD) is rapidly changing. AIMS: To identify the incidence and prevalence of biologic use within Scottish PIBD services, and to describe patient demographics and outcomes for those patients who required escalation of therapy beyond anti‐tumour necrosis factor alpha (anti‐TNFα) agents METHODS: We captured a nationwide cohort of prospectively identified patients less than 18 years of age with PIBD (A1 phenotype; diagnosed <17 years of age) within paediatric services over a 4.5‐year period (1 January 2015–30 June 2019). All patients who received infliximab, adalimumab, vedolizumab or ustekinumab during the study period and/or received their first dose of these biologics were audited retrospectively. RESULTS: Scotland‐wide PIBD‐prevalence cases increased from 554 to 644 over the study period. A total of 495 incident new‐start biological therapies were commenced on 403 PIBD patients: 295 infliximab (60%), 161 adalimumab (32%), 24 vedolizumab (5%) and 15 ustekunumab (3%). The proportion of new‐start biologics changed with infliximab initiation rates decreasing (87%–54%) while adalimumab (13%–31%), vedolizumab (0%–9%) and ustekinumab (0%–6%) all increased. The incidence rate (first dose of new biologic not including biosimilar switch) increased from 6.9% to 8.1% over the study period and point prevalence rates (any biologic use) increased from 20.2% to 43.5% ‐ an average annual percentage increase of 20%. Biosimilar penetration of new‐start anti‐TNFα agents increased from 3% to 91%. Demographics and outcomes of those patients receiving vedolizumab and ustekinumab were similar. CONCLUSIONS: Complete accrual of Scottish nationwide biologic usage within paediatric services demonstrates a rapidly changing, inexorably increasing PIBD biologics landscape.