Unfractionated heparin anticoagulation using estimated blood volume based dosing versus weight-based dosing in a Veteran population

OBJECTIVE: The purpose of this study is to compare estimated blood volume (EBV) versus weight-based (WB) dosing of unfractionated heparin in terms of safety and ability to achieve therapeutic antifactor-Xa (AF-Xa) levels. METHODS: This was a retrospective, cohort study including 32 male veterans who received UFH. Primary outcome measures included time until therapeutic anticoagulation, number of adjustments needed to achieve therapeutic anticoagulation, median AF-Xa levels and the percentage of patients who were therapeutic after the first and second levels. Safety was determined as the incidence of major and minor bleeding. RESULTS: EBV dosing may be associated with a decrease in the average time to therapeutic range (20.4 ± 16.7 hours with EBV vs. 26.8 ± 26 hours with WB; p = 0.404) and an increase in the percentage of patients achieving therapeutic anticoagulation after the first AF-Xa level (50% with EBV vs. 35.7% with WB; p = 0.611) although these results were not statistically significant. WB dosing required fewer adjustments (2.7 ± 2.9 with WB vs. 4 ± 2.6 with EBV; p = 0.192) with more patients within the therapeutic range after the second AF-Xa level (42.9% with WB vs. 33.3% with EBV; p = 0.897). There was one major and three minor bleeds in the WB dosing group versus one minor bleed for the EBV dosing cohort (p = 0.438 and p = 0.323, respectively). CONCLUSION: EBV dosing achieved quick therapeutic anticoagulation with less bleeding compared to WB dosing in a veteran population. Due to the study's limitations, larger, randomized, comparative trials are needed to confirm our findings.