Coagulation Inhibitor Potential: a study of assay variables

Introduction: The Coagulation Inhibitor Potential (CIP) assay is a further development of the Overall, Haemostatic Potential (OHP) by He et at. which monitors fibrin aggregation in plasma activated by thrombin, tissue-type plasminogen activator (t-PA) and CaCl2. CIP reflects the ability of enhanced coagulation inhibitors, antithrombin (AT) and protein C to counteract slow in vitro coagulation. Materials and methods: Plasma from 23 persons with different types of severe thrombophilic conditions were compared to normal controls. Pentasaccharide and Protac were added to enhance inhibition of coagulation. The relative effect of enhanced inhibition was calculated. Results: The assay performed equally well with tissue factor (TF) and thrombin as triggers of coagulation (P < 0.0001). Protac and rabbit thrombomodulin (TM) both demonstrated an anticoagulant effect, but only when pentasaccharide was present. Rabbit TM reduced fibrinolysis and Protac was used in the standard procedure. Pentasaccharide and Protac had a synergistic effect resulting in a clearly reduced coagulation in the normal controls, but less in persons with thrombophilia. Receiver operator characteristic (ROC) analysis indicated that at 100% sensitivity, specificity was 78% with and without t-PA. Conclusions: The improvement of the CIP by omitting t-PA allows a more rapid testing. There is a need for evaluating the CIP assay in larger patient groups. (c) 2004 Elsevier Ltd. All rights reserved.