IMPORTANCEProactive therapeutic drug monitoring (TDM), defined as individualized drug dosing based on scheduled monitoring of serum drug levels, has been proposed as an alternative to standard therapy to maximize efficacy and safety of infliximab and other biological drugs. However, whether proactive TDM improves clinical outcomes when implemented at the time of drug initiation, compared with standard therapy, remains unclear.OBJECTIVE To assess whether TDM during initiation of infliximab therapy improves treatment efficacy compared with standard infliximab therapy without TDM. DESIGN, SETTING, AND PARTICIPANTS Randomized, parallel-group, open-label clinical trial of 411 adults with rheumatoid arthritis, spondyloarthritis, psoriatic arthritis, ulcerative colitis, Crohn disease, or psoriasis initiating infliximab therapy in 21 hospitals in Norway. Patients were recruited from

IMPORTANCEProactive therapeutic drug monitoring (TDM), consisting of individualized treatment based on scheduled assessments of serum drug levels, has been proposed as an alternative to standard therapy to optimize efficacy and safety of infliximab and other biologic drugs. However, it remains unclear whether proactive TDM improves clinical outcomes during maintenance therapy.OBJECTIVE To assess whether proactive TDM during maintenance therapy with infliximab improves treatment efficacy by preventing disease worsening compared with standard infliximab therapy without TDM.DESIGN, SETTING, AND PARTICIPANTS Randomized, parallel-group, open-label clinical trial including 458 adults with rheumatoid arthritis, spondyloarthritis, psoriatic arthritis, ulcerative colitis, Crohn disease, or psoriasis undergoing maintenance therapy with infliximab in 20 Norwegian hospitals.

Brun MK, Goll GL, Jørgensen KK, Sexton J, Gehin JE, Sandanger Ø, et al. Risk factors for anti-drug antibody formation to infliximab: Secondary analyses of a randomised controlled trial.