P399 Cost-effectiveness of utilising proactive Infliximab therapeutic drug monitoring for inflammatory bowel disease in routine clinical practice

Abstract

Background: Therapeutic drug monitoring(TDM) is increasingly utilised in IBD practice to guide dosing of anti-TNFs. Proactive TDM assessment has not, however, been clearly shown to improve clinical outcomes compared with empiric dose optimisation. The aim of our study was to assess whether a proactive-TDM strategy, with the aim of dosing patients to an IFX-level in the therapeutic range, is a costeffective strategy in routine practice. Method(s): IFX TDM has been available at SJH for a 1-year period. On a pilot basis, IBD patients receiving IFX had a single trough sample collected. IFX-levels and antibody-to-IFX concentrations (ADA) were determined. IFX levels from 3 to 7 mug/l were considered therapeutic. ADA of 50 AU/ml and above were considered significant . IFX treatment decisions based on TDM were documented. Costs/ savings related to TDM use were estimated by documenting alterations to IFX regimens prompted by TDM and extrapolating annualised total dose increases / reductions. Result(s): A total of 64 IBD patients were included, 51% male, 63% Crohn's disease. Twenty-seven per cent, 43% and 30% of patients had a therapeutic, subtherapeutic and supratherapeutic IFX-level. n = 21 (33%) had significant ADA present. n = 35 patients (55%) patients had alterations to IFX dosing based on TDM: 23% had IFX dosing interval increased, 20% had IFX dosing interval decreased and 11% discontinued IFX therapy. The use of proactive-TDM was found to be cost-effective with annual savings of 70,083.34. Conclusion(s): While Anti-TNF TDM has certainly been shown to be of value in the setting of loss of response to treatment, it remains unclear whether a proactive-TDM improves clinical outcomes. Our study suggests proactive TDM may at least be a cost-effective strategy.