Impact of rivaroxaban plasma concentration on perioperative red blood cell loss.

Abstract

This study investigates the impact of preoperative calculated rivaroxaban (RXA) plasma concentration on perioperative red blood cell (RBC) loss. In this retrospective single-center study, we identified patients with RXA intake according to a preoperative determination of RXA levels within 96 hours before surgery. RXA plasma concentration at the beginning of surgery was then calculated from the last RXA intake using a single-compartment pharmacokinetic model with four categories of RXA concentration (≤20, 21-50, 51-100, and >100 μg/L). Patients were classified into surgery with high (≥500 mL) or low (<500 mL) expected blood loss. Perioperative bleeding was determined by calculating RBC loss. We analyzed 308 surgical interventions in 298 patients during the period from January 2012 to July 2018. Among patients undergoing surgery with low expected blood loss, RBC loss varied from 164 mL (standard deviation [SD], 189) to 302 mL (SD, 397) (p = 0.66), and no association of calculated RXA concentration with RBC loss was observed. In patients undergoing surgery with high expected blood loss, we found a significant correlation of calculated RXA concentration with RBC loss (Pearson's correlation coefficient, 0.29; p = 0.002). RBC loss increased with rising RXA concentration from 575 mL (SD, 365) at RXA concentration of 20 μg/L or less up to 1400 mL (SD, 1300) at RXA concentration greater than 100 μg/L. RXA concentration greater than 100 μg/L was associated with a significant increase of in RBC loss of 840 mL (95% confidence interval, 360-1300; p < 0.001). Transfusion of RBC and fresh frozen plasma units tended to increase in patients with RXA concentrations greater than 100 μg/L. The proportion of patients treated with prothrombin complex concentrate and coagulation factor XIII concentrate increased significantly with higher RXA concentrations. Only in surgery with high expected blood loss, a calculated RXA concentration of greater than 100 μg/L was associated with a significant increase of perioperative RBC loss.