Cost-effectiveness of therapeutic drug monitoring (TDM) of biologic treatment in rheumatic diseases: a narrative review

This narrative review provides a brief horizon scanning on the available literature on cost-effectiveness of therapeutic drug monitoring (TDM) in rheumatology for biological medicines. The PubMed database was used to search for articles containing the key words 'cost-effectiveness' AND 'therapeutic drug monitoring' AND 'rheumatology' or 'rheumatoid' with no limits on year of publication. CHEERS pharmacoeconomic criteria were applied to review the robustness of the studies. Out of 42 initial hits, only 4 full-text articles and 2 abstracts matched the specified search criteria fully. They conclude that proactive TDM was more cost-effective for patients with immune-mediated inflammatory diseases undergoing maintenance therapy with infliximab. For rheumatoid arthritis (RA) patients, the adalimumab dose tapering based on TDM led to an increased quality of life and quality-adjusted life year (QALY) gain and entailed lower costs. Patient-initiated service on the basis of TDM resulted in reductions in primary and secondary healthcare services, and hence, lower costs than the usual care. The use of a JAK1/JAK2 inhibitor instead of a biologic disease modifying drug (DMARD) in a treat-to-target approach is cost-effective in conventional synthetic DMARD refractory RA patients; monitoring of patients with chronic inflammatory diseases and low disease activity or in remission undergoing biological therapy can be achieved with less resources. The findings in our mini-review suggest that TDM might result in cost-saving. Given the benefit other patients may gain from the resources saved, we encourage further clinical and cost-effectiveness studies.