The relative advantages of Owren's Thrombotest and Quick's one-stage prothrombin time as guides in long-term anticoagulant therapy were studied in 24 patients. The patients were receiving either coumarin or phenindione derivatives as prophylaxis in cardiac or vascular disease. Both tests lead to results stated in percentage of normal coagulation activity. The percentages given by the Thrombotest were in general lower than those from Quick's test and fluctuated over a narrower range. During the year in which the Thrombotest was used as a guide, the incidence of thromboembolic complications was the same as during the previous year when Quick's test was so used, but the incidence of hemorrhage was less. The author believes that the Thrombotest is preferable as a guide.
Vigran IM. A New Test for Anticoagulant Therapy. JAMA. 1961;176(3):188–193. doi:10.1001/jama.1961.03040160008002