Impact of early thiopurines on surgery in 2770 children and young people diagnosed with inflammatory bowel disease: a national population-based study

Background The role of early thiopurine treatment in inflammatory bowel disease (IBD) is unproven. Aim To quantify the impact of timing and duration of thiopurines on the risk of first surgery in children and young people with IBD using a population-based cohort. Methods We constructed an incident cohort of children and young people aged <25 years, diagnosed with Crohn's disease (CD) or ulcerative colitis (UC) from 1990 to 2009. We used Cox proportional hazards modelling to determine the impact of early thiopurine use, commenced within a year of diagnosis on risk of first surgery. Results We identified 1595 and 1175 incident cases of CD and UC respectively with a mean length of follow-up of 4.3 years/person. There were 216 (13.5%) and 73 (6.2%) surgeries for CD and UC patients between 1990 and 2009 respectively. In CD among thiopurine users, the absolute risk of surgery at 5 years for early thiopurine use vs. late was 15.3% (95% CI: 10.5-22.1) vs. 22.1% (95% CI: 18.1-26.9) respectively. After adjustment, the early use of thiopurines was associated with a reduction in risk of first surgery of 39% (HR 0.61, 95% CI: 0.41-0.91) over the 20-year study period. In UC, early thiopurine use offered no additional benefit. Conclusions In Crohn's disease, early treatment with thiopurines in children and young people is associated with an appreciable reduction in the risk of surgery, but early treatment does not reduce surgical risk in UC.