A Real-world Experience of the Safety and Efficacy of Non-vitamin K Oral Anticoagulants Versus Warfarin in Patients with Non-valvular Atrial Fibrillation-A Single-centre Retrospective Cohort Study in Singapore.

INTRODUCTION: Non-vitamin K oral anticoagulants (NOACs) were shown to have better outcomes than warfarin for non-valvular atrial fibrillation (NVAF). Given limited local real-world data, this study aims to evaluate the safety and efficacy of NOACs versus warfarin for NVAF in Singapore. METHODS: This single-centre retrospective cohort study included 439 patients ≥ 21 years old that were newly prescribed with oral anticoagulants (OACs) for NVAF in 2015. Follow-ups for patients upon OAC initiation lasted either for 2 years or until the occurrence of bleeding or thromboembolism event or death (whichever was earlier). Primary endpoints included major bleeding and stroke, while secondary endpoints included overall bleeding and thromboembolic events. Time-to-events was evaluated via Kaplan-Meier survival analysis. Data on time in therapeutic range (TTR) and compliance were analysed. RESULTS: Patients were assigned to 4 groups: warfarin (157, 35.8%), rivaroxaban (154, 35.1%), apixaban (98, 22.3%) and dabigatran (30, 6.8%). With a mean age of 70.8 (±10.8) years old, the population were predominantly males (56.5%) and comprised Chinese (73.8%), Malays (18.7%) and others (7.5%). The rates of stroke per year were 0.7%, 1.7%, 2.2% and 0% for warfarin, rivaroxaban, apixaban and dabigatran, respectively (P=0.411), whereas those of major bleeding were 2.7%, 1.4%, 2.2% and 0% (P=0.560). As compared to warfarin, no significant differences were observed for risks of stroke and of major bleeding for rivaroxaban (adjusted hazard ratio (HR) 4.19, 95% confidence interval (CI) 0.68-26.05, P=0.124 and adjusted HR 0.43, 95% CI 0.12-1.59, P=0.207) and apixaban (adjusted HR 5.33, 95% CI 0.85-33.34, P=0.074 and adjusted HR 1.54, 95% CI 0.39-6.15, P=0.538). Mean TTR was 68.8% (±24.3%) for warfarin. Compliance rates for rivaroxaban, apixaban, and dabigatran were 56.6%, 59.2%, and 44.8%, respectively (P=0.177). CONCLUSION: NOACs were associated with similar stroke and major bleeding rates as warfarin for NVAF.

Comparing two predictive methods for determining serum vancomycin concentrations at a Veterans Affairs Medical Center.

PURPOSE: Two predictive methods for determining serum vancomycin concentrations (SVCs) at a Veterans Affairs medical center were compared. METHODS: The data for inpatients at the San Francisco Veterans Affairs Medical Center who received i.v. vancomycin and had vancomycin concentrations recorded in 2003 were included in this retrospective study. Creatinine clearance was estimated by the Cockcroft and Gault equation. Volume of distribution and creatinine clearance were calculated for each patient, using the Leonard and Boro method and the Rushing and Ambrose method. The Sheiner and Beal method for determining precision and bias was used to evaluate whether the two methods significantly differed in their ability to predict SVCs. RESULTS: Of the 223 patients identified, 122 patients were included, and 212 SVCs were analyzed. The population was mostly male and had a mean age of 64.1 years. There were no significant differences in 95% confidence intervals for relative precision and relative bias between the two methods. In patients whose weight was within 120% of their ideal body weight (IBW), the Leonard and Boro method was significantly more precise and less biased in predicting SVCs. In patients whose weight exceeded 120% of their IBW, the Rushing and Ambrose method was less biased and tended to be more precise, although the difference in precision was not significant. CONCLUSION: Both methods yielded similar predictability for SVCs in a veterans population. The Leonard and Boro method better predicted SVCs in patients weighing within 120% of their IBW, while the Rushing and Ambrose method appeared to be more appropriate for calculating vancomycin dosages in patients whose weight exceeded 120% of their IBW.