Application of a Precision‐Dosing Model to a Real‐World Cohort of Patients on Infliximab Maintenance Therapy: Drug Usage and Cost Analysis

Abstract

Precision‐dosing models forecast infliximab doses to achieve targeted trough concentrations in patients with inflammatory bowel disease (IBD). These models have shown to reduce non‐response and improve patient outcomes. We compared infliximab doses determined by iDOSE® precision‐dosing with standard dosing, and the associated drug costs, in patients with IBD. In this retrospective study, IBD patients treated with infliximab every eight weeks at 5 mg/kg were included. An infliximab dose was named dose X if three previous infliximab doses, laboratory values including trough infliximab concentrations and the patient's weight were recorded. The actual dose X was compared to an iDOSE®‐predicted dose X. Net drug use and costs were evaluated. 174 patients ‐ 56% male, median age 36 (IQR 29–47) years; 135 Crohn's disease and 31 ulcerative colitis were included with 417 dose X recordings. Median prior infliximab therapy was 2 (0‐4) years. Comparing actual dose X with predicted dose X, 52% and 32% of doses were subtherapeutic when aiming for trough concentrations of 5–10 and 3–7 μg/ml respectively. Treatment costs increased by 102% and 29% for the two trough ranges respectively. On multivariate regression analysis, subtherapeutic infliximab concentrations were associated with ulcerative colitis compared with Crohn's disease [OR: 9.81, 95% CI: 1.28‐75.40, p = 0.028] and pre‐dose X infliximab trough concentration [OR: 0.07, 95% CI: 0.03‐0.15, p<0.001]. Over half of maintenance infliximab drug doses were too low to achieve infliximab blood concentrations of ≥5 μg/ml. While applying precision‐dosing may improve patient outcomes, drug costs could be considerably greater.This article is protected by copyright. All rights reserved