Major haemorrhagic complications during oral anticoagulant therapy in a Danish Population‐based cohort

Abstract. Steffensen FH, Kristensen K, Ejlersen E, Dahlerup JF, S~rensen HT (University of Aarhus and Aarhus University Hospital, Arhus, and Aalborg Hospital, Aalborg, Denmark). Major haemorrhagic complications during oral anticoagulant therapy in a Danish population‐based cohort. 1 Intern Med 199 7; 242: 497‐503. Objectives: To estimate the incidence of bleeding leading to death or hospital admission in out‐patients treated with oral anticoagulants. Design: Population‐based historical cohort study 1 January 1992 to 31 September 1994. Setting: The County of North Jutland, Denmark (488 000 inhabitants). Subjects: Six hundred and eighty‐two consecutive patients commencing oral anticoagulant therapy. Main outcome measures: Fatal bleeding or bleeding demanding hospital admission. Results: In 756 treatment‐years of follow‐up, there were 45 major haemorrhagic events (6.0 per 100 treatment‐years) in 42 patients, of which seven (0.9 per 100 treatment‐years) were fatal. The risk of a first major haemorrhagic episode was highest during the first 90 days of treatment compared with duration above one year (incidence rate ratio, IRR, 1.9; 95% CI, 0.8‐4.1). The rate was highest above the age of 60 years, 6.8 per 100 treatment‐years, compared with 2.9 per 100 treatment‐years below 60 years (IRR 2.3; 95% CI, 1.0–5.6). The rate for a bleeding event was slightly higher in females than in males (IRR 1.3; 95% CI, 0.7‐2.3), but did not vary according to type of anticoagulant drug. Conclusions: The reported rates of major bleeding in this routine community setting implied a higher bleeding risk than was found in randomized trials or when patients are monitored in specialist anticoagulation clinics.