Week 2 Adalimumab Levels Predict Short-term Clinical Remission in Patients With Inflammatory Bowel Disease

Background and Goals: The role of early proactive therapeutic drug level monitoring for anti-tumor necrosis factor therapies is unclear. We aimed to determine whether a week 2 serum trough level in patients with inflammatory bowel disease (IBD) using adalimumab may predict clinical outcomes. Materials and Methods: This was a retrospective study of consecutive IBD patients with a week 2 serum adalimumab level available. Receiver operating characteristic curve analysis was conducted to determine an optimal week 2 threshold level for adalimumab. Patients above the threshold were compared for the primary outcome of week 12 clinical remission (CR) and the secondary outcome of short-term endoscopic healing. Multivariate logistic regression analysis was performed to evaluate the relationship between week 2 adalimumab level and CR. Results: Forty-six patients had a week 2 adalimumab level performed. Receiver operating characteristic curve analysis suggested an optimal adalimumab level of 11.9 mcg/mL based on the area under the curve. Patients with week 2 adalimumab levels >11.9 mcg/mL had higher odds of week 12 CR than those with levels below or equal to this threshold (odds ratio=3.34, 95% confidence interval: 1.01-12.11, P=0.04). Other covariates were not found to have a significant association with the primary outcome. The rate of short-term endoscopic healing was numerically higher in patients with adalimumab week 2 levels above 11.9 mcg/mL; however, was not statistically significant (71.4% vs. 28.5%, P=0.11). Conclusions: Serum adalimumab levels at week 2 appears to be a predictor of short-term CR. Further research should explore whether patients with a week 2 adalimumab level equal to or below 11.9 mcg/mL benefit from early dose optimization.