Bleeding, especially Intra-cerebral hemorrhage (ICH), is a serious complication of oral anticoagulant (OAC) use. In the Netherlands, acenocoumarol and phenprocoumon are mainly used under dose regulation guided by specialized anticoagulation clinic. Schols and colleagues retrospectively analyzed all adult cases of confirmed non-traumatic ICH while on OAC between 2007 and 2009.
Authors report that acenocoumarol was used by 134 (79.8%) patients, 20 (11.9%) patients were using phenprocoumon and 14 (8.3%) patients used a combination of OAC with another antithrombotic drug. Of all ICH cases, 168 (25.8%) were OAC-associated and 153 of these (91.1%) were first-ever OAC- ICH. The absolute risk of OAC-ICH was 0.46% per patient-year of OAC treatment.
This reported absolute risk, although slightly higher than previously reported rate, is well within the range of bleeding risk reported in clinical trials using Warfarin. It is to be kept in mind that this is an estimated risk only and that usually controlled environment of trials tends to underestimate the risk.
I think that slightly higher annual risk in this study is reflective of increasing number of patients using anticoagulants in a more controlled (specialized clinics) environment through which adverse event reporting tends to be more accurate. While the exact numbers may not be applicable to population is the United States, this study provides good estimation of OAC-ICH risk that can be used in discussion with the patients while making decision about use of OAC.