Oral Anticoagulant Therapy and its Control: An International Survey
This is a survey made for the International Study Group for Anticoagulant Control. A questionnaire was sent to 37 countries and there were 31 replies. The information obtained indicated that the most widely used test in oral anticoagulant therapy is the one stage prothrombin estimation. There was a great diversity in the method of reporting prothrombin time results ; percentage activity of normal on the basis of saline dilution curve was marginally the most popular. Only 3 countries had any national or regional systems for anticoagulant control.Recommendations for the therapeutic range of dosage varied widely. The upper limit in one country may be the lower limit in another. The variation of therapeutic range was was still considerable in different countries even when a standard thromboplastin was used.The survey provided valuable data indicating the need for urgent measures to provide a uniform basis for clinical dosage of anticoagulant drugs, and its laboratory control. Given these wide variations, it would be impossible to compare the efficacy of oral anticoagulant therapy from country to country or to conduct meaningful multicentre trials.