long-term anticoagulant treatment

suMMARY 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 treat-ment, 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 pro-thrombin 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 pro-thrombin 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. The coumarin group of anticoagulants was devel-oped by Link in the late 1930's (Link, 1943-1944) and their use in man first reported by Butt et al. in 1941. Since then they have been used to reduce the risk of embolic and thrombotic complications in certain patients. Over the years the spectrum of disease for which long-term oral anticoagulation is recommended has widened (British Medical,Journal, 1972; Rogers and Sherry, 1976; Staffurth et al., 1977). The therapeutic objective of achieving the lowest possible rate of thromboembolic complica-tions must be weighed against the risk of haemor-rhagic complications of therapy. The present study reviews the haemorrhagic complications of anti-coagulation experienced in one anticoagulant clinic over a 7-year period