Diagnostic sensitivity of coagulation assays and ClotChip at low DOAC concentrations. (A) Prothrombin time (PT) results in DOAC samples with drug concentrations less than 100 ng/mL. (B) Activated partial thromboplastin time (aPTT) results in the same cohort. Rivaroxaban: n = 12; apixaban: n = 8; dabigatran: n = 1. The horizontal line in panels (A) and (B) represents the normal reference range for PT and aPTT, respectively. (C) ClotChip Tpeak levels in low DOAC concentrations. The horizontal line represents the upper limit of normal range (i.e., Tpeak = 530 seconds). Each dot in panels (A)–(C) represents the mean of duplicate measurements for each individual sample. (D) Sensitivity and specificity of PT, aPTT assays, and ClotChip Tpeak in the prespecified DOAC cohort. DOAC, direct oral anticoagulant.