The level of factor X coagulation and the risk of adverse reactions during treatment with rivaroxaban and apixaban in patients with non-valvular atrial fibrillation

Introduction . Xa factor inhibitors are a significant treatment option for patients with atrial fibrillation, as they assist in reducing the risk of stroke. However, there has not been enough research into the levels of X-factor in these patients. Aim . To assess the impact of blood clotting factor X on the risk of adverse drug events (ADEs) in patients receiving apixaban or rivaroxaban treatment. Materials and methods . The study involved 102 patients with atrial fibrillation who were administered Xa inhibitors: 56 received rivaroxaban and 46 received apixaban. Adverse drug reactions were documented, which were noted in the patient's medical records during drug administration. The concentration of the X factor was measured using photocolorimetry with reagents designed to determine the concentration of the factor X — AssaySense Human Factor X (FX) Chromogenic Activity Assay Kit (AssayPro, USA). Results . In patients receiving apixaban therapy, the X factor concentration was lower in 32.6% of cases and in 43.5% of patients, it was higher than the reference value. In contrast, in patients receiving rivaroxaban therapy, these indicators were lower in 26.8% of cases and higher in 51.8% of patients. Overall, according to the medical records, there were 37 adverse reactions in 29 patients, including 23 (41.1%) ADEs in 19 patients (33.9%) receiving rivaroxaban and 14 (30,4%) ADEs in 10 patients (21.7%) taking apixaban. The level of X factor was statistically significantly associated with the risk of stroke, with an AUC ROC of 0.720 and p-value of 0.05, and with minor bleeding, with an AUC ROC of 0.735 and p-value 0.003. An increase in the X factor level above 12.6 pg/mL increased the risk of stroke by 9.4-fold (95% CI: 1.9-74.3, p = 0.034), while a decrease below 10.5 pg/mL increased the risk of bleeding by 3.2-fold (95% CI: 1.2-8.7, p = 0.021). Conclusion . The level of the X factor in individuals with atrial fibrillation exhibits a wide range of variability. Deviations from the reference values, either below or above, can significantly impact the risk of experiencing minor bleeding or suffering a stroke, respectively.