Problems encountered in long-term treatment with anticoagulants.

The course of long-term anticoagulant therapy in 114 out-patients has been evaluated over a three-month period. The evaluation was based on the registration of information from the clinical records and from two personal interviews with each patient. The patients had attended the Anticoagulation Clinic for 141 weeks on the average. The prothrombin complex activity (PP%) level was siginificantly lower in patients with bleeding episodes. An apparently higher PP% level in patients with thromboembolic manifestations was not significant. No bleeding was observed when the PP% was above 25. Warfarin resulted in relatively bleeding episodes and more PP% values within the desired range (10-25) than phenprocoumon and bishydroxycoumarin. The role of age, but not of moderate hypertension, as a risk factor was confirmed. A probable adverse interaction of the anticoagulant and other drugs was found in 37.5% of the situations in which an interaction could be expected according to the literature.