The normalized activated protein C sensitivity ratio (nAPCsr) was measured using two thrombin generation assays. In the first assay, coagulation was triggered in defibrinated plasma with tissue factor in the presence and absence of activated protein C and the amount of thrombin captured in complex with a2-macroglobulin over 30 minutes was taken as a measure for thrombin generation and used to calculate the nAPCsr (nAPCsr α2M-IIa).14 In the second assay, the nAPCsr (nAPCsr CAT) was determined by measuring thrombin generation in the presence and absence of activated protein C in full plasma in real-time with a fluorogenic thrombin substrate using calibrated automated thrombinography (CAT).19 The CV's of the nAPCsr α2M-IIa and nAPCsr CAT were 3.5% and 7%, respectively.