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Purpose: Low-dose rivaroxaban is often given to patients with atrial fibrillation (AF) around the world, but the rationale for its use remains unclear. We aimed to compare the efficacy and safety of standard- or low-dose rivaroxaban in patients with AF through systematic review of literature with meta-analysis. Methods: We searched PubMed, Web of Science, EMBASE, Clinical Trials.gov, the Cochrane Library, and Bayer trial website from inception of each database until June 2020. Randomized controlled trials (RCTs) and cohort studies were included in the meta-analysis. A random-effects model was employed to calculate the pooled effect estimates. Results: Two RCTs and 17 cohort studies were included in the qualitative analysis. Indirect comparison of RCTs showed no significant difference between the two rivaroxaban dosages in risk of efficacy or safety outcomes (p > 0.05). Indirect comparison of cohort studies showed a lower risk of MACE among Caucasians in standard-dose group (HR 0.779; 95% CI 0.687–0.884; p < 0.001). Bleeding outcomes did not differ significantly between the two dosage regimens in Asian or Caucasian populations, except that the standard dose was associated with higher risk of major bleeding among elderly Caucasian patients (HR 1.329; 95% CI 1.141–1.547; p < 0.001). The quality of evidence was rated ranging from very low to low for all the efficacy and safety outcomes. Conclusion: In Caucasians with AF, standard-dose rivaroxaban may prevent MACE significantly better than low-dose treatment. Further studies in Asians are needed to verify the advantages of the standard dose. [ABSTRACT FROM AUTHOR]

Background: For patients taking factor Xa (FXa) inhibitors who have life-threatening bleeding, emergency surgery, drug interactions, etc., a rapid and precise assay is needed to monitor for potential medication failure, to assess safety during periprocedural anticoagulation management, and to manage the care of chronically anticoagulated patients. Anti-factor Xa (anti-Xa) activity assays have been recommended in guidelines, but the evaluation of different calibrations of anti-Xa activity assays and the data on the recommended range are still limited, especially in the Asian population. Methods: This is a nationwide multicenter methodology exploratory study in an Asian population, including nine hospitals from Beijing, Shanghai, Liaoning, Shandong, Jiangsu, Anhui, Henan, Chongqing, and Fujian. A total of 485 healthy volunteers and 219 patients taking rivaroxaban or apixaban (single dose) were enrolled in the study. High-performance liquid chromatography-tandem mass spectrometry (HPLC-MS) was employed to detect plasma rivaroxaban and apixaban. The prothrombin time (PT), activated partial thromboplastin time (APTT), and levels of anti-Xa activity were tested as pharmacodynamic parameters in plasma samples. We evaluated the correlation of anti-Xa activity and blood concentration via HPLC-MS, and then compared the two methods of target drug-calibrated and low-molecular-weight heparin (LMWH)-antithrombin–calibrated anti-Xa activity. Correlations between variables were examined using Pearson's correlation analysis. Logistic regression was applied to evaluate significant differences in anti-Xa activity and blood concentration, using models adjusted by baseline characteristics. Results: The results suggested anti-Xa activity had better correlation with blood concentrations of apixaban and rivaroxaban than APTT and PT (p < 0.001). Target drug-calibrated anti-Xa activity had better correlation with HPLC-MS results at every dose level and blood collection time (p < 0.001). The expected concentrations (ng/mL) derived from rivaroxaban-calibrated assays of rivaroxaban 10 mg, 15 mg, and 20 mg were about 210, 330, and 270 at peak concentrations, and 28, 44, and 58, respectively, at the trough concentrations. Conclusions: In this study, we confirm that target drug calibration of anti-Xa activity is a better quantitative detection method for oral direct FXa inhibitors than LMWH-calibrated anti-Xa activity in clinical practice, and expected peak–trough levels are recommended for the Asian population. [ABSTRACT FROM AUTHOR]

Background: Due to the high risk of ischemic and arterial or venous bleeding events in atrial fibrillation (AF) or venous thromboembolism (VTE) patients with renal impairment (RI), selection of appropriate anticoagulant regimen is important. Therefore, we systematically reviewed and compared the safety and effects of oral anticoagulants in AF and VTE patients with RI. Methods: Eligible articles were identified through a literature search in PubMed, Embase, ClinicalTrials.gov, and the Cochrane Library for studies published between January 2008 and November 2020. Network meta-analysis was conducted with STATA 14.0 to analyze the effects and safety of each drug with regard to different levels of renal function. Results: 15 studies including 82,931 patients (76,957 with AF and 5974 with VTE) were analyzed. Compared with those of warfarin, the risk ratios of effect and safety outcomes of apixaban were 0.70 (95% confidence interval [CI] 0.60–0.82) and 0.56 (95% CI 0.42–0.76) in AF patients and 0.33 (95% CI 0.19–0.59) and 0.95 (95% CI 0.68–1.34) in VTE patients. Apixaban had the first or second highest probability of being ranked first with respect to surface under the cumulative ranking curve (SUCRA) scores in the prevention of major bleeding events, while in the prevention of ischemic events, rivaroxaban showed a higher SUCRA score (0.78–0.92) in mild RI patients and dabigatran showed a higher SUCRA value (0.90–0.99) in moderate RI patients. Conclusions and Relevance: In the systematic review and meta-analysis, for AF or VTE patients with RI, direct oral anticoagulants performed comparably to or better than warfarin with regard to safety and effects. The network meta-analysis indicated that for patients with mild RI, apixaban might be safer for patients with a lower risk of ischemic events, while rivaroxaban might be suitable for patients with a lower risk of bleeding events. For patients with moderate RI, apixaban could reduce the risk of ischemic events without increasing the risk of bleeding events. For AF patients with severe RI, apixaban, rivaroxaban, and warfarin showed a similar effect. These results might provide suggestions for clinical arterial and venous thrombosis prevention. [ABSTRACT FROM AUTHOR]