P537 Is anti-TNF therapeutic drug monitoring of value in IBD patients in clinical remission?

Abstract

Introduction: Therapeutic drug monitoring (TDM) and the concept of treat-to-target are yielding better outcomes in patients with inflammatory bowel disease (IBD). Serum levels of anti-TNF therapy are associated with clinical response and mucosal healing. This study aims to evaluate the association between serum levels of anti-TNF therapy and faecal calprotectin, disease activity scores, endoscopic findings and biochemical markers in IBD patients. Method(s): Serum drug levels were measured in patients presenting between 2014 and March 2016. Demographic information and clinical characteristics were retrieved retrospectively from medical records. Disease activity scores (CDAI, Mayo), endoscopic findings, biochemical data (CRP, platelet, albumin) and faecal calprotectin levels were obtained close to the time of serum levels of anti-TNF therapy. Patients with sub-therapeutic and therapeutic serum levels of anti-TNF therapy were compared using Fisher exact tests and t-tests. Data collection is ongoing. Result(s): The 52 patients with available serum levels were included. Patients had a mean age of 34 years (SD = 13.6), and 65% were female. The majority (79%) had Crohn's disease, and 89% were on maintenance infliximab. Thirty-five (67%) patients had sub-therapeutic drug levels. All 17 (100%) patients with therapeutic drug levels had CDAI score <150 or partial Mayo score of <2 (p = 0.041). Conversely, only 17/41 (41%) patients in clinical remission had therapeutic levels. Thirteen of 14 (93%) patients with sub-therapeutic and 3/7 (43%) with therapeutic drug levels had elevated faecal calprotectin (>50 mg/kg), whilst 4/5 (80%) patients who had normal faecal calprotectin (FC