Age‐ and weight‐adjusted warfarin initiation nomogram for ischaemic stroke patients

Objectives Specific guidelines for initial dosing of warfarin in ischaemic stroke patients have not been developed. Therefore, we have developed an age- and weight-adjusted warfarin initiation nomogram (AW-WIN) for ischaemic stroke patients and then evaluated the efficacy and safety of AW-WIN compared with physician-determined warfarin dosing (PDWD). Methods The age- and weight-adjusted warfarin initiation nomogram was administered to 104 acute ischaemic stroke patients between January 2008 and February 2009. A historical control group (PDWD) of 96 patients was selected from comparable patients who were discharged with warfarin during the previous year. Time-to-therapeutic international normalized ratios (INRs) and the incidence of excessive anticoagulation were compared in the AW-WIN and PDWD groups. Results The general characteristics, risk factors, and stroke mechanism of the AW-WIN and PDWD groups did not differ significantly. The mean time to INR ≥ 2.0 was significantly shorter in the AW-WIN than in the PDWD group (4.9 ± 0.7 vs. 6.2 ± 0.8 days, P = 0.0008). After adjustment for potential confounding variables, the AW-WIN group reached target INR faster than the PDWD group (hazard ratio, 1.76; 95% confidence interval, 1.26–2.45; P = 0.001). The time-to-therapeutic INR ≥1.7 was shorter (P = 0.0002), the proportion of patients with therapeutic INR (2–3) at 5 days was higher (P = 0.002), and the rate of excessive anticoagulation of ≥3.5 INR during hospitalization was lower (P = 0.024) in the AW-WIN than in the PDWD group. Conclusions AW-WIN reduces the time to target INR and the risk of excessive anticoagulation. AW-WIN may be an efficient and safe method of anticoagulation during the acute phase of ischaemic stroke.