PMS68 PROMONITOR FOR THERAPEUTIC DRUG MONITORING IN PATIENTS WITH SEVERE RHEUMATOID ARTHRITIS TREATED WITH ADALIMUMAB IN ENGLAND AND WALES

Abstract

Adalimumab is used for severe rheumatoid arthritis (RA), but its efficacy is hampered by the presence of low drug levels and anti-drug antibodies (ADAs). Although not currently part of standard National Health Service (NHS) practice, patients who achieve remission may be eligible for supervised dose tapering. This could be done through the use of enzyme-linked immunosorbent assay (ELISA) tests, capable of measuring both drug and ADAs concentrations, alongside conventional clinical assessment. In this study, the economic outcomes of adding therapeutic drug monitoring (TDM) using Promonitor (Grifols–Progenika) assays to standard care in people with severe RA (Disease Activity Score 28>5.1) treated with adalimumab who had either achieved remission or low disease activity were evaluated. A cost-utility analysis based on a decision tree model was informed by a non-randomised trial INGEBIO identified following a systematic review. Since there is a substantial variation in clinical practice for TDM testing, dose-tapering and flare-management strategies in people with RA, and the actual cost of adalimumab to the NHS, incremental cost-effectiveness ratios (ICERs) were estimated for various clinically plausible scenarios and discounts for the list price of adalimumab (Humira®, AbbVie). Costs and resource use were considered from the NHS and Personal Social Services perspective. No discounting was applied to costs and effects due to the short-term time horizon of 18 months. ICERs in all except two scenarios were located in the north-east quadrant of the cost-effectiveness plane and ranged from £4,230 to £164,009 per quality-adjusted life-year gained. When the frequency of testing was one test per year or the cost of phlebotomy appointments to collect trough samples was excluded, the intervention dominated standard care. The cost-effectiveness of TDM with Promonitor for optimizing adalimumab treatment in people with RA is highly uncertain due to data limitations. Thus, future clinical studies are warranted.