The impact of body composition variability on coagulation monitoring in patients on direct oral factor Xa inhibitors for treatment of venous thromboembolism

Background/objectives Evidence for the first-line treatment of venous thromboembolism (VTE) by use of direct oral anticoagulants (DOACs) is based on stratification by body-mass index (BMI) and total body weight, but does not consider body composition – defined as the distribution of fat mass (FM) and fat-free mass (FFM). Variability in body composition exists among patients with normal BMI, but is anticipated to be markedly greater in the context of overweight and obesity. Methods The BIARIVA prospective, single-center, cross-sectional study was conducted to assess whether body composition affects blood coagulation monitoring parameters in patients on therapeutic-dose anticoagulant treatment for VTE with oral factor (F.) Xa inhibitors rivaroxaban or edoxaban. Patients were qualified for inclusion into the study if they were categorized into one of the specified BMI categories; 18–25, 30–35, or > 35 kg/m 2 . Body composition was determined by two bioelectrical impedance analysis (BIA) methods. The primary endpoint was the association between body composition parameters and coagulation measurements in patients treated with rivaroxaban or edoxaban, assessed by correlation analysis. Results Thirty-six patients on rivaroxaban and 35 patients on edoxaban were finally analyzed. The main finding in this study was a significant negative correlation observed in the edoxaban group for the absolute FFM with anti-F.Xa and plasma concentration peak levels (BIA method 1: r s = −0.439, p = 0.008; BIA method 2: r s = −0.431, p = 0.010) and with the absolute increase from trough to peak in plasma concentration levels (BIA method 1 and 2: r s = −0.446, p = 0.007) and in anti-F.Xa levels (BIA method 1: r s = −0.445, p = 0.007; BIA method 2: r s = −0.444, p = 0.008). No significant correlations of body composition measures with coagulation parameters were found in the rivaroxaban group. Conclusions This study suggests that body composition might influence specific coagulation measurements in patients treated with edoxaban, but further research is required to finally determine the role of body composition in this context and to evaluate clinical implications.