Analysis of risk factors involved in oral-anticoagulant-related intracranial haemorrhages.

We examined risk factors for intracranial bleeding while on oral anticoagulants (OACs) in 68 patients admitted to hospital over a 6-year period, and 204 out-patient controls followed-up in an OAC clinic. Under multivariate analysis, significant risk factors for OAC-related intracranial bleeds were hypertension (OR (95%CI) 2.69 (1.04-6.97), duration of OAC therapy < or =12 months (OR 3.74 (1.21-11.56)), duration > or =96 months (OR 0.25 (0.07-0.88)), and International Normalized Ratio on admission >4.5 (OR 10.92 (2.46-48.43)). A logistic regression model including the above variables along with a history of 'cerebrovascular disease' (OR 2.32 (0.98-5.46)) correctly predicted intracranial bleeding (or its absence) during OAC therapy in 85% of all patients. The risk associated with advanced age and concomitant aspirin use was not significantly increased in this analysis. It is important to achieve tight control of INR, particularly in the early months of treatment. Patients with previous cerebrovascular disease are at increased risk of intracranial bleeding on warfarin, and hypertensive patients should have especially close monitoring and optimal control of their blood pressure.