We aimed to compare effectiveness and safety of the non‐vitamin K antagonist oral anticoagulants (NOACs) vs. warfarin for stroke prevention in nonvalvular atrial fibrillation (NVAF) in a developing country where anticoagulation control with warfarin is suboptimal. A real‐world study was conducted among patients with NVAF in Thailand receiving NOACs and warfarin from 9 hospitals during January 2012 to April 2018. Propensity‐score weighting was used to balance covariates across study groups. Cox regression models were used to compare the risk of thromboembolism, major bleeding, and net adverse clinical events across matched cohorts. A total of 2,055 patients; 605, 604, 441, and 405 patients receiving warfarin, rivaroxaban, dabigatran, and apixaban, respectively, were included. Median (interquartile range) time in therapeutic range (TTR) for warfarin users was 49.5% (26.6%–70.3%). Compared with warfarin, NOACs were associated with a significant reduction in major bleeding either when analyzed as a group (adjusted hazard ratio (HR) (95% confidence interval (CI)) of 0.46 (0.34–0.62) or by each agent. Compared with warfarin users with poor TTR, apixaban (adjusted HR 0.48, 95% CI 0.26–0.86, P = 0.013) and dabigatran (adjusted HR 0.44, 95% CI 0.21–0.90, P = 0.025) were associated with a lower risk of thromboembolism, in addition to markedly lower risk of major bleeding. In a healthcare system where anticoagulation control with warfarin is suboptimal, use of NOACs was associated with a profound reduction in major bleeding. The effectiveness and safety advantages of NOACs were more pronounced compared with warfarin users with low TTR.

Aims This study aimed to evaluate the prescriber compliance to the approved labels of direct oral anticoagulants (DOACs) and impact of appropriateness of dosing on clinical outcomes. Methods A retrospective study was conducted using simple‐stratified random sampling of adult patients receiving ≥6 months of DOACs for various indications during 2013–2017 in 10 tertiary care hospitals. Patients were classified into 3 dosing groups including approved dose, underdosing and overdosing based on the Thai Food and Drug Administration‐approved labels. Cox proportional hazard models were used to evaluate the impact of different dosings on thromboembolic and bleeding events. Results From 1200 patients included in the data analysis, prescribing of DOACs was consistent with the approved indications in 1130 cases (94.2%) while 70 patients (5.8%) received DOACs despite having contraindications or with off‐label usage. Among 1026 cases of dosing evaluation cohort, 688 patients (67.1%) received approved doses. There were 227 (21.9%) and 110 (10.7%) cases of underdosing and overdosing, respectively. Multivariate analysis showed that underdosing was associated with an increased risk of thromboembolism 3.023 (95% confidence interval [CI]: 1.291–7.080; P = .011) while overdosing was associated with an increased risk of bleeding requiring hospitalization (adjusted hazard ratio, 3.045; 95% CI, 1.501–6.178; P = .002) and Bleeding Academic Research Consortium type 2 or more (adjusted hazard ratio, 2.196; 95% CI, 1.083–4.452; P = .029). Conclusion Prescribers’ compliance to approved indications were high. However, 1/3 of DOAC prescriptions were inconsistent with approved dosing. Dosing deviation was associated with an increase in adverse clinical outcomes.

Aims This study aimed to evaluate the performance of HAS‐BLED and ORBIT scores in predicting bleeding risk among Asian patients with nonvalvular atrial fibrillation (NVAF) using direct‐acting oral anticoagulants (DOACs). Methods A retrospective chart review was conducted among adult patients receiving DOACs for ≥6 months during January 2013 to December 2017 in 10 tertiary care hospitals in Thailand. The area under the receiver operating curve (AUROC) method or C‐statistic was used to test the diagnostic accuracy for bleeding risk classification of HAS‐BLED and ORBIT scores. The predictive performances of the two scores were compared using DeLong's method. Results A total of 961 NVAF patients, 52.5% warfarin‐naïve and 47.5% warfarin‐experienced, with mean age of 74.25 ± 10.08 years, were included in the analysis. Mean HAS‐BLED and ORBIT scores of the cohort were 1.98 ± 1.10 and 2.37 ± 1.71, respectively. During the mean follow‐up time of 1.55 ± 1.13 years, 34 patients experienced major bleeding (2.28 events/100 patient‐year). For the overall cohort, both the HAS‐BLED and ORBIT scores showed similarly moderate predictive performance on bleeding with C‐statistic (95% confidence interval) of 0.65 (0.57‐0.74) and 0.64 (0.56‐0.71), respectively. There was no statistical significance between the two scores (P = .62). Analysis based on the status of previous warfarin use was consistent with the overall cohort. Based on the calibration analysis, both HAS‐BLED and ORBIT scores possessed moderate ability to identify those who experienced major bleeding from those who did not. Conclusion Both HAS‐BLED and ORBIT bleeding risk scores had moderate predictive performance in Asian NVAF patients receiving DOACs.