Treatment with biologic agents is costly and the mechanisms available for inflammatory bowel disease (IBD) remain limited. It is important to optimise the benefit and cost-effectiveness of their use. Therapeutic drug monitoring (TDM) is a strategy to help achieve this, through the measurement of drug and anti-drug antibody concentrations. The Building Research in IBD Globally (BRIDGe) groups ‘Anti-TNF Opimizer’, an online tool that helps interpretation of TDM and clinical decision-making.Methods
We performed a retrospective study of IBD patients on infliximab (IFX) or adalimumab (ADA) at our institution, undergoing TDM between Jan 16-Mar 17. TDM was performed using a drug-tolerant ELISA (IDKmonitor, Immundiagnostik). Disease activity was defined by the combination of clinical symptoms and evidence of biochemical (CRP >10; FCP >150), endoscopic or radiological activity. Clinical decision-making was compared to recommendations made by the BRIDGe ‘Anti-TNF Optimizer’ tool, which suggests that objective evidence should be sought in all cases of suspected primary non-response (PNR) and loss of response (LOR). Subsequent disease course was evaluated using a Physicians Global Assessment (PGA), which took into account clinical, biochemical, endoscopic and/or radiological activity and the need to progress to surgery. Outcomes were described as ‘favourable’ or ‘unfavourable’. Groups were compared using Fisher’s exact test (GraphPad Prism V.7.0a).Results
60 patients were included: 30 IFX and 30 ADA. Indications for TDM: LOR 45 (75%), PNR 8 (13%), routine monitoring during remission 7 (12%). Objective evidence of inflammation was sought in all 53 cases of LOR/PNR and found present in 42 (79%). Two patients were lost to follow up and were not included in the final analysis. Of these 40, subsequent clinical management was in keeping with BRIDGe recommendations in 19 (48%).Results
Of the 19 LOR/PNR patients managed as per BRIDGe recommendations, 15 (79%) achieved a subsequent favourable outcome. The rate of subsequent favourable outcome in the group who were not managed in accordance with BRIDGe was significantly lower at 3/21 (14%, p<0.0001).Conclusions
The rate at which objective evidence of inflammation was sought amongst our patients with symptoms suggestive of PNR/LOR was good. However, clinical decision-making deviated from BRIDGe recommendations in majority of cases and this appeared to adversely impact disease course. Results therefore, suggest that using an evidence-based, expert consensus, online tool to guide biologic decision-making with the results of biologic TDM provides benefit in IBD outcomes.