A Multicenter Study of Anticoagulation Parameters When Using Heparin and Warfarin

Anticoagulation with heparin and warfarin is used in the treatment of several diseases including cerebrovascular disease. While the most effective therapeutic range of anticoagulation is unclear, some investigators have found an increased risk of bleeding complications with more intense anticoagulation. Recent studies have suggested that lower levels of anticoagulation may be as efficacious as high levels but with a reduced incidence of bleeding complications. In order to better assess the anticoagulation parameters used by neurologists and house officers, we performed a questionnaire survey at six major medical centers. Responses were obtained from 30 attending neurologists and 52 house officers. Attending physicians and house officers selected mean partial thromboplastin times of 57.7 s and 63.3 s, respectively. The mean prothrombin time (PT) was 21.0 s for attending neurologists and 19.4 s for house officers. The average PT ratio was 1.82 for attending neurologists and 1.69 for house officers. Forty percent of attending neurologists and 17.7% of house officers specified PT ratios of 2.0 or greater. These results indicate that many physicians may be using warfarin in dosages above recommended guidelines.