The results of this randomized controlled study do not encourage the regular use of therapeutic drug monitoring (TDM) during the initiation of infliximab therapy for improving disease remission rates in cases of chronic immune-mediated inflammatory diseases.

To compare the efficacy of proactive TDM during the introduction of infliximab (a chimeric monoclonal antibody) therapy and standard infliximab therapy without TDM.

This randomized clinical study comprised of 411 adults (51% women) with spondyloarthritis, rheumatoid arthritis, psoriatic arthritis, Crohn's disease, ulcerative colitis, or psoriasis starting with infliximab therapy. The patients were randomized to:

• TDM group (207 patients) who received proactive TDM with dose and interval adjustments as per the planned monitoring of serum drug levels and antidrug antibodies
• Standard therapy group (204 patients) with standard therapy with no drug and antibody monitoring.

Clinical remission of the disease at week 30 was the primary outcome.

All in all, the full analysis set comprised 398 patients out of the total study population (198 patients in the TDM group and 200 patients in the standard therapy group) who got their randomized intervention. At week 30, 100 (50.5%) of 198 patients in the TDM group and 106 (53.0%) of 200 patients in the standard therapy group achieved clinical remission. About 68% and 70% of patients in the TDM and standard therapy group reported as having adverse events.

Proactive TDM when used for over a period of 30 weeks did not considerably improve the clinical remission rates in immune-mediated inflammatory disease patients initiating infliximab therapy.