A 7-year analysis of haemorrhage in patients on long-term anticoagulant treatment.

Abstract

Anticoagulant treatment reduces the risk of embolic and thrombotic complications in certain patients but hemorrhagic problems of the treatment have been less critically assessed. In this study, 501 documented outpatients treated during 1970-1977, comprising 1199 patient-yr of treatment, were analyzed to clarify the iatrogenic risks of hemorrhage associated with oral anticoagulants [warfarin and dindevan]. Forty-one patients experienced 51 hemorrhages of sufficient severity to seek medical advice. The incidence was 8.2% among patients and 4.3% per treatment yr. There were 24 occasions when the hemorrhage was potentially lethal and 2 patients died. In 23 of these 24 events, the prothrombin ratio at the time of hemorrhage was prolonged beyond the therapeutic range. The prothrombin ratio was only known to be prolonged beyond the therapeutic range on 1 of the 27 occasions with less serious hemorrhages. The risk of hemorrhage was unrelated to age and was greatest in those patients in whom the prothrombin ratio proved difficult to control from the outset and in men with an aortic valve prosthesis. There was no cumulative risk in the first 3 yr of treatment but a trend for increased risk between 4-7 yr. It is in these groups with a high risk of bleeding that prothrombin control and patient education call for the closest attention.