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

Anticoagulant treatment reduces the risk of embolic and thrombotic complications in certain patients but haemorrhagic problems of the treatment have been less critically assessed. In this study 501 fully documented outpatients treated between 1970 and 1977, comprising 1199 patient-years of treatment, have been analysed in an attempt to clarify the iatrogenic risks of haemorrhage associated with oral anticoagulants. Forty-one patients experienced 51 haemorrhages of sufficient severity to seek medical advice. The incidence was 8'2 per cent among patients and 4*3 per cent per treatment year. There were 24 occasions when the haemorrhage was potentially lethal and 2 patients died. In 23 of these 24 events, the prothrombin ratio at the time of haemorrhage was prolonged beyond the therapeutic range. In contrast, the prothrombin ratio was only known to be prolonged beyond the therapeutic range on 1 of the 27 occasions with less serious haemorrhages. The risk of haemorrhage was unrelated to age and was greatest in those patients in whom the prothrombin ratio had proved difficult to control from the outset and in men with an aortic valve prosthesis. There was no cumulative risk in the first 3 years of treatment but a trend for increased risk between 4 and 7 years. It is in these groups with a high risk of bleeding that prothrombin control and patient education call for the closest attention.