The Clinical and Cost-Effectiveness of 4 Enzyme-Linked Immunosorbent Assay Kits for Monitoring Infliximab in Crohn Disease Patients: Protocol for a Validation Study.

BACKGROUND: Currently, treatment decisions for people with Crohn disease are based on clinical judgment and trial and error. Consequently, people may continue to receive high drug dosages and experience unnecessary toxicity when it is possible to reduce or discontinue without a detrimental effect on clinical outcomes. Therapeutic drug monitoring (TDM) involves regularly testing blood samples for drug and antibody levels that could help clinicians identify the optimal treatment strategy and pre-empt treatment failure. However, heterogeneity in the assays can lead to a discrepancy in results and difficulties in decision-making. Standardization of the kits, and therefore results, would allow clinicians to optimize the use of biologics. Currently, there is also a lack of evidence for the cost-effectiveness of TDM using commercial test kits. OBJECTIVE: This study aims to analyze the clinical and cost-effectiveness of 4 commercial enzyme-linked immunosorbent assay (ELISA) kits (LISA TRACKER, IDKmonitor, Promonitor, and RIDASCREEN) to generate evidence which could support a recommendation for wider adoption in the National Health Service. METHODS: We propose to carry out a prospective-retrospective predictive biomarker validation study using the blood samples and clinical/utilization data collected during the ongoing SPARE trial (NCT02177071). A total of 200 stored samples from people with Crohn's disease who respond to treatment with infliximab will be used along with clinical and cost data from the trial. We will investigate the relationship between the drug and antidrug antibody levels with the main clinical outcomes (relapse rate at 2 years and time spent in remission), as well as resource utilization and quality of life. RESULTS: Funding is being sought to conduct this research. CONCLUSIONS: This is the first study to compare the 4 ELISA kits for monitoring infliximab in patients with Crohn disease. It aims to address the uncertainties in the potential benefits of using the technologies for TDM. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): PRR1-10.2196/11218.