“…27,28,48 In one study-a single-centre retrospective cohort study of children aged 5-18 years with IBD-serum infliximab levels during maintenance treatment did not show significant correlation with patientreported clinical status. 46 In a prospective observational study of 52 patients [34 CD,18 UC], who were developing secondary failure to infliximab, reactive therapeutic drug monitoring, strongly predicted the likelihood of achieving mucosal healing following infliximab dose intensification. 49 Finally, a retrospective cohort analysis of doseoptimisation events based on therapeutic dose monitoring [n = 149] or empirical decisions [n = 163] demonstrated that the former approach was associated with higher endoscopic remission rates and fewer relapses.…”