Exploration of the correlation between anti-factor Xa activity and blood concentration in patients over 60 years old treated with rivaroxaban

Zhang Ruiqi; Du Jiali; Liu Meilin

doi:10.3760/j.issn.1673-4777.2025.03.002

Abstract：Objective To evaluate the association between anti-factor Xa activity(AXA)and rivaroxaban blood concentration in elderly patients over 60 years old treated with rivaroxaban,and to establish a linear regression model for the relationship between AXA and blood concentration.Methods This study was a prospective cohort study.Fifty patients aged ≥60 years with complete clinical data and indications for anticoagulant therapy who were hospitalized in the Department of Geriatric Medicine,Peking University First Hospital from March 2022 to March 2023 and received rivaroxaban were enrolled.After continuous administration of rivaroxaban for at least 3 days,blood samples were drawn to detect the trough and peak values of AXA and the trough and peak values of blood drug concentration.Linear regression models were used to evaluate the relationship between AXA and blood concentration.Results In the study population,there was a linear correlation between the trough value of AXA and the trough value of blood concentration.Taking the AXA trough value of rivaroxaban 3 days after administration as the independent variable and the trough value of blood drug concentration as the dependent variable,the linear regression model was constructed,and the following results were obtained:①(y)=10.378+160.185 × trough value of AXA.That was,for every 1 kIU/L increase in the trough value of AXA,the trough value of blood concentration increased by 170.563 μg/L.The determination coefficient was 0.730,the Durbin-Watson test value was 1.845,the model statistical test F=129.538,P＜0.001,and the residual was in accordance with normal distribution.There was a linear correlation between the peak value of AXA and the peak value of blood concentration.Taking the peak value of AXA after taking rivaroxaban for 3 days as the independent variable and the peak value of blood drug concentration as the dependent variable,the linear regression model was constructed,and the following results were obtained:②y=33.600+119.449 × peak value of AXA.That was,when the peak value of AXA increased by 1 kIU/L,the peak blood concentration increased by 153.049 μg/L.The determination coefficient was 0.656,the Durbin-Watson test value was 2.083,the model statistical test F=91.655,P＜0.001,and the residual was in accordance with normal distribution.Conclusion There is a linear regression model between AXA and blood concentration of rivaroxaban.In clinical practice,the predicted bleeding concentration can be calculated by the linear regression model between AXA and blood concentration,which can be compared with the target value to evaluate the anticoagulant strength and guide further treatment.