Incidence, clinical impact and risk of bleeding during oral anticoagulation therapy.

Bleeding is the most important complication of oral anticoagulation (OAC) with vitamin K-antagonists. Whilst bleeding is unavoidably related to OAC, it may have a great impact on the prognosis of treated subjects by leading to discontinuation of treatment, permanent disability or death. The yearly incidence of bleeding during OAC is 2%-5% for major bleeding, 0.5%-1% for fatal bleeding, and 0.2%-0.4% for intracranial bleeding. While OAC interruption and/or antagonism, as well as administration of coagulation factors, represent the necessary measures for the management of bleeding, proper stratification of the individual risk of bleeding prior to start OAC is of paramount importance. Several factors, including advanced age, female gender, poor control and higher intensity of OAC, associated diseases and medications, as well as genetic factors, have been proven to be associated with an increased risk of bleeding. Most of these factors have been included in the development of bleeding prediction scores, which should now be used by clinicians when prescribing and monitoring OAC. Owing to the many limitations of OAC, including a narrow therapeutic window, cumbersome management, and wide inter- and intra-individual variability, novel oral anticoagulants, such as factor Xa inhibitors and direct thrombin inhibitors, have been recently developed. These agents can be given in fixed doses, have little interaction with foods and drugs, and do not require regular monitoring of anticoagulation. While the novel oral anticoagulants show promise for effective thromboprophylaxis in atrial fibrillation and venous thromboembolism, definitive data on their safety and efficacy are awaited.