An international collaborative study to establish the World Health Organization 2nd International Standard for Factor VII Concentrate: communication from the SSC of the ISTH

The 1st International Standard (IS) for factor VII concentrate (97/592) was established by the Expert Committee on Biological Standardization (ECBS) of the World Health Organization (WHO) in 1998 [1]. A potency of 6.3 IU was assigned to the preparation with clotting and chromogenic methods, relative to the 2nd IS FII, FVII, FIX and FX plasma (94/746) and normal plasma pools. This reference material has been used for potency assignment to human coagulation FVII concentrate preparations used to treat FVII deficiency, and for FVIIcontaining prothrombin complexes used for reversal of anticoagulant treatment. As stocks of the 1st IS are low, an international collaborative study was organized to calibrate a replacement.