Age and body weight adjusted warfarin initiation program for ischaemic stroke patients

Despite its proven effect, anticoagulation is not recommended to the acute ischaemic stroke due to the risk of bleeding complications. The purpose of this study is development of individualized warfarin initiation program for acute or subacute stroke patients.

Among stroke patients who regularly visited out-patient clinics, we included patients who have continuously taken the same dose of warfarin as the prothrombin time remained at target International Nomarlized Ratio (INR). We assessed potential variables that affect the maintenance dose of warfarin. Using these variables, we developed an individualized warfarin initiation program.

The median warfarin maintenance dose (interquartile range) in the 321 included patients was 4 (3-5) mg per day. Age (adjusted R(2) = 0.221, P < 0.001) and body weight (added to age, adjusted R(2) = 0.238, P = 0.008) were significant predicting factors of the dose. We classified the maintenance doses into high (HG), standard, and low group (LG) based on the distribution of maintenance doses. Decision tree analysis categorized younger (or=55 kg) patients into HG, and very old (>or=80 years old) or low body weight (<55 kg among those >56 years old) patients into LG. We recommend 7 mg of warfarin as a standard initial dose, but 10 mg was recommended for HG patients and 5 mg for LG.

We expect that this individualized program may reduce the time to target INR without excessive anticoagulation. Further prospective studies are needed to reveal the efficacy and safety of applying this program for acute stroke patients.