Effect on Plasma Protein S Activity in Patients Receiving the Factor Xa Inhibitors.

AIMS: Measurement of protein S (PS) activity in patients taking direct oral anticoagulants (DOACs) using reagents based on a clotting assay results in falsely high PS activity, thus masking inherited PS deficiency, which is most frequently seen in the Japanese population. In this study, we investigated the effect of factor Xa (FXa) inhibitors on PS activity using the reagent on the basis of the chromogenic assay, which was recently developed in Japan. METHODS: The study enrolled 152 patients (82 males and 70 females; the average age: 68.5±14.0 years) receiving three FXa inhibitors (rivaroxaban, edoxaban, and apixaban). PS activity was measured using the reagents on the basis of the clotting and chromogenic assays. RESULTS: PS activity measured by the clotting assay reagents exhibited falsely high values depending on the plasma concentrations of FXa inhibitors in patients taking either rivaroxaban or edoxaban. However, none of the three FXa inhibitors affected PS activity when measured using the chromogenic assay. CONCLUSION: In patients taking rivaroxaban or edoxaban, inherited PS deficiency is likely missed because the levels of PS activity measured using the reagents based on the clotting assay are falsely high. However, we report that three FXa inhibitors do not affect PS activity measured by the chromogenic assay. When measuring the levels of PS activity in patients undergoing DOACs, the principles of each reagent should be understood. Furthermore, plasma samples must be collected at the time when plasma concentrations of DOACs are lowest or the DOAC-Stop reagent should be used.

[Deep vein thrombosis in Noto Peninsula earthquake victims].

The earthquake occurred in the Noto Peninsula in the northern part of Ishikawa prefecture, Japan, at 9:25 a.m. on March 25th 2007. Medical activities for prevention of deep vein thrombosis (DVT), early detection of DVT, and early treatment of DVT were performed immediately after the earthquake on the basis of a previous report regarding earthquake disasters. This report described the conditions involved in the development of DVT. General inhabitants in shelters were examined by questionnaires, venous ultrasonography of lower limb, and blood tests. The DVT-positive rate was 10.6% (21 cases/198 cases), and the soleal vein was the most common location of DVT accounting for 71.4% of cases(20 lower limbs/28 lower limbs). Plasma levels of fibrin/fibrinogen degradation products and D-dimer in the DVT-positive group (20 cases) were significantly higher than those in the DVT-negative group(162 cases) (P<0.03). No deaths or cases of serious illness caused by DVT were reported in the earthquake. The medical activities described here were effective due to the past experience and the cooperation of many people.