Background/AimsThe optimal timing for initiation of anti-tumor necrosis factor (TNF) therapy in Crohn’s disease (CD) is still debated. Little is known about the clinical outcomes of early versus late administration of anti-TNF agents, especially in Asian CD patients. We aimed to evaluate the impact of early anti-TNF therapy on clinical outcomes in Korean CD patients.MethodsUsing the Korean National Health Insurance Claims database, we collected data on patients diagnosed with CD who received anti-TNF therapy for more than 6 months between 2010 and 2016. Early initiation of anti-TNF therapy was defined as those starting infliximab or adalimumab therapy within 1 year of diagnosis. The following outcomes were assessed using a Cox proportional hazard model: abdominal surgery, CD-related emergency room (ER) visit, CD-related hospitalization, and new corticosteroid use.ResultsAmong 1,207 patients, 609 were early initiators of anti-TNF. Late anti-TNF initiation (> 1 year after diagnosis) was associated with increased risk of surgery (adjusted hazard ratio [aHR], 1.64; 95% confidence interval [CI], 1.05 to 2.55) and tended to be associated with increased risk of ER visit (aHR, 1.38; 95% CI, 0.99 to 1.94). However, there were no significant differences in the risk of hospitalization and corticosteroid use between early and late initiators.ConclusionsEarly anti-TNF therapy among Korean CD patients within 1 year of diagnosis was associated with better clinical outcomes than late therapy, such as lower surgery and ER visit rates. Our results suggest that aggressive medical intervention in the early stages of CD may potentially change the course of this disease.