Supratherapeutic INR as a surrogate for depletion of protein C via parallel reduction in factor VII. (A) Reciprocal of the INR (1/INR) vs factor VII levels. The area below the horizontal dashed line indicates INR values >3.5. There was a strong association between 1/INR and VII (see “Supratherapeutic INR as a surrogate marker for severe PC depletion: regression analyses”). (B) Factor VII vs PC activity levels. There was a strong association between factor VII and PC activity levels (see text for analyses, interpretation, and discussion).