Interactions between thrombophilic genetic mutations and clinical bleeding in patients on chronic oral anticoagulant treatment.

We studied the prevalence of genetic thrombophilic mutations in patients on chronic oral anticoagulant treatment (OAT) who had bleeding complications. In a case-control study we found ten (12.8%) carriers of factor V Leiden and two (2.5%) carriers of the PT20210A mutation among 78 patients with a history of moderate-severe bleeding while on OAT, and seven (4.4%) and four (2.5%), respectively, among 156 matched patients with no bleeding while on OAT (odds ratio 3.1+/-1.6, p=0.026). In patients on chronic OAT, FV Leiden is a risk factor for moderate-severe bleeding.