Proactive therapeutic concentration monitoring of infliximab may improve outcomes for patients with inflammatory bowel disease: Results from a pilot observational study

Background: Infliximab (IFX) is effective in the treatment of inflammatory bowel disease; however, the effect is often not durable. It is unknown if proactive therapeutic concentration monitoring (TCM) of IFX improves outcomes. Methods: This is a retrospective observational study examining the use of proactive TCM and titration of IFX to a target concentration for patients with inflammatory bowel disease in clinical remission at a tertiary care center. The primary aim was to describe the clinical course of patients who had proactive TCM. A secondary analysis was done to assess if this strategy was superior to the standard of care. Results: Forty-eight patients were identified as having proactive TCM. Fifteen percent had an initial undetectable trough concentration. Twenty-five percent (12 of 48) of patients escalated IFX after the first proactive TCM while 15% (7 of 48) of patients de-escalated IFX therapy over the study period. A control group of 78 patients was identified. Patients who had proactive TCM had a greater probability of remaining on IFX than controls (hazard ratio, 0.3; 95% confidence interval, 0.1-0.6; log rank test; P = 0.0006). The probability of remaining on IFX was greatest for patients who achieved a trough concentration .5 mg/mL (hazard ratio, 0.03; 95% confidence interval, 0.01-0.1; P , 0.0001 versus trough ,5 mg/mL). Fewer patients in the proactive TCM group stopped IFX (10% versus 31%, P = 0.009). Conclusions: In this pilot observational study, proactive TCM of IFX frequently identified patients with low or undetectable trough concentrations and resulted in a greater probability of remaining on IFX.