TNF and inflammatory bowel disease: Retrospective data and metanalysis suggest a proactive TDM approach is associated with a reduction in treatment failure, hospitalization, need for IBD-related surgery and may increase drug durability.17,18 Results of controlled studies, however, have failed to consistently illustrate the benefits of proactive TDM over a reactive approach.19–21 No prospective studies have compared anti-TNF treatment durability with respect to TDM and dose optimization approaches.