Utility of Drug Levels and Anti-Drug Antibodies When Starting TNF inhibitors Save

A prospective cohort of 331 patients tested for anti-adalimumab (n=160) and anti-etanercept (n-171) antibodies after initiation of their TNF inhibitor therapy. At 3 months, ADAbs and low adalimumab drug levels were significant predictors of lack of 12 month EULAR response (area under curve 0.71, 95% CI 0.57-0.85). Etanercept levels were not significantly associated with 12 month EULAR response after adjustment. BMI ≥ 30 and poor adherence were associated with lower drug levels.