Anticoagulant treatment as a risk factor for primary intracerebral haemorrhage.

Forty one (14.2%) of 288 patients with primary intracerebral haemorrhage occurring between September 1985 and December 1989 in Central Finland were on anticoagulant treatment at the onset of symptoms. In a sample of 29,000 subjects from the same population the prevalence of anticoagulant treatment was 1.6% in those aged 40 years or older. The estimated age adjusted odds ratio of being on anticoagulant treatment at the time of primary intracerebral haemorrhage was 6.7 (95% CI from 4.5 to 9.9). The risk was highest during the first year of anticoagulation. Overtreatment (thrombotest value < 5%) was slightly more common among the patients. The haematoma volumes measured from the CT scans were similar in patients on anticoagulant treatment and those not anticoagulated. The case fatality rate during the first week and the mortality during follow up of 32 months were slightly higher, and the functional outcome slightly worse in the anticoagulated group.