Maarten Cozijnsen

123 Chapter 6 Benefits and risks of combination therapy in children with IBD Four retrospective cohort studies presented analyses comparing combination with monotherapy for the treatment of UC. Armuzzi et al (40) included 126 UC patients treated with IFX of whom 71 also received IMs. More patients treated with combination vs. those treated with monotherapy had steroid-free remission at six and 12 months (63% vs. 40%, P=0.009; 59% vs. 31%, P=0.002). The rate of both steroid-free remission and mucosal healing at 12 months was higher in the former (42% vs. 20%, P=0.008). Additionally, more thiopurine naïve patients treated with combination therapy achieved steroid-free remission at six and 12 months than thiopurine experienced patients (80% vs. 50%, P=0.009; 80% vs. 39%, P<0.001). Hayes et al (41), within a cohort of 85 UC patients receiving IFX, observed an increased duration of IFX therapy at 1 year in combination vs monotherapy treated patients (90% vs 61%, P=0.016). Furthermore, combination therapy resulted in higher IFX levels (20.4 mg/L vs. 10.5 mg/L, P=0.025) and less frequent ATI formation (4.5% vs. 33%, P=0.031). Within a cohort of 109 UC patients with a median follow-up of 46 months, Jeuring et al (42) found higher risk for loss of response in patients treated with monotherapy vs. combination therapy (hazard ratio 2.4 (1.1-5.1)). Garcia-Bosch et al (43), in a very small cohort of 48 UC patients treated with ADA, reported response rates of 74% (26/35) among patients receiving concomitant IM vs. 62% (8/13, P≈0.5) in those treated with ADA alone. Thus far, increased efficacy has only been demonstrated in adult UC patients treated with IFX plus AZA compared with IFX monotherapy. Like in CD, combination therapy seems to reduce the occurrence of ATIs and increase IFX drug levels, and it may be more efficacious in AZA naïve patients than AZA experienced patients.