Maarten Cozijnsen

109 Chapter 5 Adalimumab therapy in children with infliximab-refractory CD Secondly, the efficacy assessment was suboptimal. We used clinical disease activity indices and not mucosal healing or markers for mucosal healing to evaluate adalimumab efficacy. Furthermore, the wPCDAI could not be calculated at each time point and a PGA was used in the remainder. Lastly, not all patients were treated in the same way. Patients received different adalimumab induction dosages and different concurrent medication. Decisions concerning their treatment were based on the judgement of the treating physician, as were decisions concerning treatment cessation. Variations in confounders may have biased our outcome data as well as the sub analyses. Conclusions and generalizability This study demonstrates that in clinical practice adalimumab is an effective therapy for infliximab refractory pediatric CD patients with only limited side effects. We therefore recommend its usage in these otherwise difficult to treat patients. Well powered, long- term pharmacovigilance studies are needed to further establish the safety of adalimumab therapy in pediatric CD patients, especially regarding late onset adverse events, such as malignancies. Adalimumab appears to be less effective in the treatment of infliximab non-responders and patients previously failing infliximab without the presence of ATI. To further establish these efficacy differences, they should be confirmed in larger cohorts. Because of its clinical relevance, research should attempt to elucidate possible differences in disease mechanism, so that disease mechanism specific therapy can be given, and costly, ineffective therapy can be avoided.