BACKGROUND Treatments for inflammatory bowel diseases (IBD) have evolved in the era of biologics. However, the real-world data on their usage patterns and sequencing are still limited.

OBJECTIVES We aimed to investigate treatment persistence and dose intensification of first- and second-line biologics in patients with IBD.

DESIGN In this retrospective, cohort study using nationwide claims data, 13,087 patients with IBD initiating biologic therapy between 2010 and 2020 were identified.

METHODS Treatment persistence and dose intensification during the first 2 years and switching patterns of biologics were analysed while identifying predictors of non-persistence.

RESULTS As a first-line treatment of Crohn's disease (CD), ustekinumab had a lower risk for non-persistence compared to infliximab [adjusted hazard ratio (aHR), 0.69, p = 0.048]. Second-line ustekinumab and vedolizumab showed the highest and lowest persistence (79.2% and 54.9%), respectively. As a first-line treatment of ulcerative colitis (UC), golimumab had a higher risk for non-persistence compared to infliximab (aHR, 1.68, p < 0.001). Second-line golimumab also showed a significantly lower persistence rate than adalimumab and vedolizumab. The risk of non-persistence was higher in UC than in CD (first line: aHR, 1.97; second line: aHR, 1.39; p < 0.001), and in the second-line treatment than in the first-line treatment for CD (aHR, 1.55; p < 0.001). The cumulative rate of dose intensification was highest with ustekinumab for CD (first line, 43.3%, second line, 69.1%) and adalimumab for second-line UC (40.7%). It was significantly increased in second-line therapy in CD, but not in UC. Among switchers of first-line anti-tumour necrosis factor-α inhibitor therapy, after all biologics were approved, 69% of CD patients and 78.4% of UC patients switched to other classes of second-line treatment.

CONCLUSION Ustekinumab had higher persistence in the first-line treatment of CD, while golimumab had lower persistence for first- and second-line treatments of UC. Dose intensification rates varied, with the highest cumulative rates observed for ustekinumab in CD and adalimumab in second-line UC.