In 2013 a novel commercial test was launched (Anser 
Wilcoxon rank sum test, and linear and logistic regression methods were applied in the statistical analysis to test hypotheses. The study design was observational and uncontrolled.
Of a total of 14,239 tests conducted, 5509 had information available that pertained to reasons for ordering, of which disease monitoring (46.9%) was the most common. Median serum ADL level with standard maintenance dosing (40 mg, biweekly) was 8.8 μg/mL (n = 2901). A five-fold decrease in median serum ADL levels occurred with very low ATA titers (1.7-3 U/mL, p < .0001). Serum ADL levels decreased further with ATA >7 U/mL (p < .0001). A total of 16.5% of patients were ATA positive, of whom 61.9% had low ATA (1.7-7 U/mL); 87.9% of ATA-positive patients had serum ADL levels ≤4.4 μg/mL. Expression of inflammatory markers significantly increased with high ATA (>7 U/mL). An inverse relationship between ADL and ATA was observed (R
In this real-world cross-sectional population, serum ADL levels decreased with increasing ATA titers, with low ATA titers (≤7 U/mL) significantly reducing serum ADL compared to ATA-negative samples. Expression of inflammatory markers significantly increased at higher ATA titers (>7 U/mL). These findings highlight the clinical importance of monitoring patients for drug levels and anti-drug antibody titers.