Risk factors for intracranial hemorrhage during vitamin K antagonist therapy in patients with nonvalvular atrial fibrillation: A case-control study.

BACKGROUND: Intracranial hemorrhage (ICH) is the most fearful side effect of oral anticoagulant therapy. It is still unclear which risk factor is involved in ICH during vitamin K antagonists (VKAs) treatment and if commonly used bleeding risk scores are able to predict ICH.

PURPOSE: Search for individual risk factors and bleeding risk scores (HAS-BLED, ATRIA and ORBIT) associated with ICHs in patients with atrial fibrillation treated with VKAs.

METHODS: This is a retrospective case-control study in a single Thrombosis Center. During a 7-year period, patients with nonvalvular atrial fibrillation (NVAF) who developed ICH during VKAs were identified as cases. Four control patients matched for gender, age and length of VKAs were assigned to each case. The association between considered risk factors and ICHs was evaluated using a linear logistic regression method and expressed as odds ratio. Receiver operator characteristic (ROC) curves to assess the predictive ability of bleeding risk scores HAS-BLED, ATRIA and ORBIT were also evaluated.

RESULTS: Fifty-one cases of ICH, most of whom were 80 years of age or older (72.5%), were retrieved from the Thrombosis Center's database. Compared to 204 controls, no individual risk factors were associated with ICH. Poor ability to predict ICH was also found using ROC curves (C-statistic for HAS-BLED, ATRIA, and ORBIT were 0.55, 0.53 and 0.54, respectively).

CONCLUSIONS: ICHs during VKA therapy preferentially occur in very elderly patients. The risk of ICH is not predicted by the commonly used risk scores.