To Jacob de Wolff, a Dutch doctor concerning Pulmonary embolism: 1. the distinction between risk and underlying factors is very vague because often overlapping, Therefore it is more useful to combine both to Causes or Etiology. 2. Warfarine is all the time used where it has to be in general the coumarin derivates. As also a Dutch medical doctor. Nicolaas19 (talk) 23:07, 13 December 2014 (UTC)