Adalimumab real-world dosage pattern and predictors of weekly dosing: Patients with Crohn's disease in the United States

Background and aims: To determine the real-world dosage pattern of adalimumab and predictors for weekly dosing in Crohn's disease (CD). Methods: Patients with CD receiving adalimumab maintenance therapy (≥ 3 dispensing events within 1. year) were identified from a large specialty pharmacy database in the United States (March 2007-July 2008). Weekly dosing rates (≥ 2 consecutive weekly doses after the first dispensing event) for a 12-month period were estimated with Kaplan-Meier methods. Predictors for weekly dosing were identified using Cox proportional-hazards regression. Results: The overall adalimumab weekly dosing rate was 11.3% (151 of 1335 patients). The 12-month cumulative risk of weekly dosing was 15.5%. Patients who received a 160-/80-mg induction regimen had half the risk for weekly dosing compared with other induction regimens (hazard ratio, 0.48; 95% confidence intervals 0.33-0.7; p< 0.0001). Weekly dosing rates were significantly lower in the West and South vs. the Northeast. Conclusions: The adalimumab weekly dosing rate in a real-world, managed-care setting is less than that in clinical trials and academic centres. Geographic region and not starting on 160-/80-mg induction therapy were significantly associated with weekly adalimumab use for patients with CD.