Ischaemic and haemorrhagic stroke associated with non-vitamin K antagonist oral anticoagulants and warfarin use in patients with atrial fibrillation: a nationwide cohort study.

Non-vitamin K antagonist (VKA) oral anticoagulants (NOACs) are widely used as stroke prophylaxis in non-valvular atrial fibrillation (AF), but comparative data are sparse. To compare dabigatran, rivaroxaban, and apixaban vs. VKA and the risk of stroke/thromboembolism (TE) and intracranial bleeding in AF. Using Danish nationwide registries (2011-15), anticoagulant-naïve AF patients were identified when initiating VKA or an NOAC. Outcomes were stroke/TE and intracranial bleeding. Multiple outcome-specific Cox regression was performed to calculate average treatment effects as standardized differences in 1-year absolute risks. Overall, 43 299 AF patients initiated VKA (42%), dabigatran (29%), rivaroxaban (13%), and apixaban (16%). Mean CHA2DS2-VASc (SD) score was: VKA 2.9 (1.6), dabigatran 2.7 (1.6), rivaroxaban 3.0 (1.6), and apixaban 3.1 (1.6). Within patient-specific follow-up limited to the first 2 years, 1054 stroke/TE occurred and 261 intracranial bleedings. Standardized absolute risk (95% CI) of stroke/TE at 1 year after initiation of VKA was 2.01% (1.80% to 2.21%). In relation to VKA, the absolute risk differences were for dabigatran 0.11% (-0.16% to 0.42%), rivaroxaban 0.05% (-0.33% to 0.48%), and apixaban 0.45% (-0.001% to 0.93%). For the intracranial bleeding outcome, the standardized absolute risk at 1 year was for VKA 0.60% (0.49% to 0.72%); the corresponding absolute risk differences were for dabigatran -0.34% (-0.47% to - 0.21%), rivaroxaban -0.13% (-0.33% to 0.08%), and apixaban -0.20% (-0.38% to - 0.01%). Among anticoagulant-naïve AF patients, treatment with NOACs was not associated with significantly lower risk of stroke/TE compared with VKA, but intracranial bleeding risk was significantly lower with dabigatran and apixaban.

Staerk L ，Fosbøl EL ，Lip GYH ，Lamberts M ，Bonde AN ，Torp-Pedersen C ，Ozenne B ，Gerds TA ，Gislason GH ，Olesen JB ... -  《-》

Comparative effectiveness and safety of non-vitamin K antagonist oral anticoagulants and warfarin in patients with atrial fibrillation: propensity weighted nationwide cohort study.

 To study the effectiveness and safety of the non-vitamin K antagonist oral anticoagulants (novel oral anticoagulants, NOACs) dabigatran, rivaroxaban, and apixaban compared with warfarin in anticoagulant naïve patients with atrial fibrillation.  Observational nationwide cohort study.  Three Danish nationwide databases, August 2011 to October 2015.  61 678 patients with non-valvular atrial fibrillation who were naïve to oral anticoagulants and had no previous indication for valvular atrial fibrillation or venous thromboembolism. The study population was distributed according to treatment type: warfarin (n=35 436, 57%), dabigatran 150 mg (n=12 701, 21%), rivaroxaban 20 mg (n=7192, 12%), and apixaban 5 mg (n=6349, 10%).  Effectiveness outcomes defined a priori were ischaemic stroke; a composite of ischaemic stroke or systemic embolism; death; and a composite of ischaemic stroke, systemic embolism, or death. Safety outcomes were any bleeding, intracranial bleeding, and major bleeding.  When the analysis was restricted to ischaemic stroke, NOACs were not significantly different from warfarin. During one year follow-up, rivaroxaban was associated with lower annual rates of ischaemic stroke or systemic embolism (3.0% v 3.3%, respectively) compared with warfarin: hazard ratio 0.83 (95% confidence interval 0.69 to 0.99). The hazard ratios for dabigatran and apixaban (2.8% and 4.9% annually, respectively) were non-significant compared with warfarin. The annual risk of death was significantly lower with apixaban (5.2%) and dabigatran (2.7%) (0.65, 0.56 to 0.75 and 0.63, 0.48 to 0.82, respectively) compared with warfarin (8.5%), but not with rivaroxaban (7.7%). For the combined endpoint of any bleeding, annual rates for apixaban (3.3%) and dabigatran (2.4%) were significantly lower than for warfarin (5.0%) (0.62, 0.51 to 0.74). Warfarin and rivaroxaban had comparable annual bleeding rates (5.3%).  All NOACs seem to be safe and effective alternatives to warfarin in a routine care setting. No significant difference was found between NOACs and warfarin for ischaemic stroke. The risks of death, any bleeding, or major bleeding were significantly lower for apixaban and dabigatran compared with warfarin.

Larsen TB ，Skjøth F ，Nielsen PB ，Kjældgaard JN ，Lip GY ... -  《BMJ-British Medical Journal》

Effectiveness and safety of reduced dose non-vitamin K antagonist oral anticoagulants and warfarin in patients with atrial fibrillation: propensity weighted nationwide cohort study.

Objective To examine clinical effectiveness and safety of apixaban 2.5 mg, dabigatran 110 mg, and rivaroxaban 15 mg compared with warfarin among patients with atrial fibrillation who had not previously taken an oral anticoagulant.Design Propensity weighted (inverse probability of treatment weighted) nationwide cohort study.Setting Individual linked data from three nationwide registries in Denmark.Participants Patients with non-valvular atrial fibrillation filling a first prescription for an oral anticoagulant from August 2011 to February 2016. Patients who filled a prescription for a standard dose non-vitamin K antagonist oral anticoagulant (novel oral anticoagulants, NOACs) were excluded. To control for baseline differences in the population, a propensity score for receipt of either of the four treatment alternatives was calculated to apply an inverse probability treatment weight.Intervention Initiated anticoagulant treatment (dabigatran 110 mg, rivaroxaban 15 mg, apixaban 2.5 mg, and warfarin).Main outcome measures Patients were followed in the registries from onset of treatment for the primary effectiveness outcome of ischaemic stroke/systemic embolism and for the principal safety outcome of any bleeding events.Results Among 55 644 patients with atrial fibrillation who met inclusion criteria, the cohort was distributed according to treatment: apixaban n=4400; dabigatran n=8875; rivaroxaban n=3476; warfarin n=38 893. The overall mean age was 73.9 (SD 12.7), ranging from a mean of 71.0 (warfarin) to 83.9 (apixaban). During one year of follow-up, apixaban was associated with higher (weighted) event rate of ischaemic stroke/systemic embolism (4.8%), while dabigatran, rivaroxaban, and warfarin had event rates of 3.3%, 3.5%, and 3.7%, respectively. In the comparison between a non-vitamin K antagonist oral anticoagulant and warfarin in the inverse probability of treatment weighted analyses and investigation of the effectiveness outcome, the hazard ratios were 1.19 (95% confidence interval 0.95 to 1.49) for apixaban, 0.89 (0.77 to 1.03) for dabigatran, and 0.89 (0.69 to 1.16) for rivaroxaban. For the principal safety outcome versus warfarin, the hazard ratios were 0.96 (0.73 to 1.27) for apixaban, 0.80 (0.70 to 0.92) for dabigatran, and 1.06 (0.87 to 1.29) for rivaroxaban.Conclusion In this propensity weighted nationwide study of reduced dose non-vitamin K antagonist oral anticoagulant regimens, apixaban 2.5 mg twice a day was associated with a trend towards higher rates of ischaemic stroke/systemic embolism compared with warfarin, while rivaroxaban 15 mg once a day and dabigatran 110 mg twice a day showed a trend towards lower thromboembolic rates. The results were not significantly different. Rates of bleeding (the principal safety outcome) were significantly lower for dabigatran, but not significantly different for apixaban and rivaroxaban compared with warfarin.

Nielsen PB ，Skjøth F ，Søgaard M ，Kjældgaard JN ，Lip GY ，Larsen TB ... -  《BMJ-British Medical Journal》

Standard and reduced doses of dabigatran, rivaroxaban and apixaban for stroke prevention in atrial fibrillation: a nationwide cohort study.

Comparative data of non-vitamin K antagonist oral anticoagulants (NOAC) are lacking in patients with atrial fibrillation (AF). We compared effectiveness and safety of standard and reduced dose NOAC in AF patients. Using Danish nationwide registries, we included all oral anticoagulant-naïve AF patients who initiated NOAC treatment (2012-2016). Outcome-specific and mortality-specific multiple Cox regressions were combined to compute average treatment effects as 1-year standardized differences in stroke and bleeding risks (g-formula). Amongst 31 522 AF patients, the distribution of NOAC/dose was as follows: dabigatran standard dose (22.4%), dabigatran-reduced dose (14.0%), rivaroxaban standard dose (21.8%), rivaroxaban reduced dose (6.7%), apixaban standard dose (22.9%), and apixaban reduced dose (12.2%). The 1-year standardized absolute risks of stroke/thromboembolism were 1.73-1.98% and 2.51-2.78% with standard and reduced NOAC dose, respectively, without statistically significant differences between NOACs for given dose level. Comparing standard doses, the 1-year standardized absolute risk (95% CI) for major bleeding was for rivaroxaban 2.78% (2.42-3.17%); corresponding absolute risk differences (95% CI) were for dabigatran -0.93% (-1.45% to -0.38%) and apixaban, -0.54% (-0.99% to -0.05%). The results for major bleeding were similar for reduced NOAC dose. The 1-year standardized absolute risk (95% CI) for intracranial bleeding was for standard dose dabigatran 0.19% (0.22-0.50%); corresponding absolute risk differences (95% CI) were for rivaroxaban 0.23% (0.06-0.41%) and apixaban, 0.18% (0.01-0.34%). Standard and reduced dose NOACs, respectively, showed no significant risk difference for associated stroke/thromboembolism. Rivaroxaban was associated with higher bleeding risk compared with dabigatran and apixaban and dabigatran was associated with lower intracranial bleeding risk compared with rivaroxaban and apixaban.

Staerk L ，Gerds TA ，Lip GYH ，Ozenne B ，Bonde AN ，Lamberts M ，Fosbøl EL ，Torp-Pedersen C ，Gislason GH ，Olesen JB ... -  《-》

Initiation of anticoagulation in atrial fibrillation: which factors are associated with choice of anticoagulant?

The use of non-vitamin K antagonist oral anticoagulants (NOACs) for stroke prophylaxis in atrial fibrillation (AF) is increasing rapidly. We compared characteristics of AF patients initiated on NOACs versus vitamin K antagonists (VKAs). Using Danish nationwide registry data, we identified AF patients initiating either a VKA or a NOAC from 22 August 2011 until 30 September 2016. We compared patient characteristics including age, gender, comorbidities, concomitant pharmacotherapy and CHA2 DS2 -VASc and HAS-BLED scores in patients initiated on a VKA, dabigatran, rivaroxaban or apixaban. Differences were examined using multivariable logistic regression models. The study population comprised 51 981 AF patients of whom 19 989 (38.5%) were initiated on a VKA, 13 242 (25.5%) on dabigatran, 8475 (16.3%) on rivaroxaban and 10 275 (19.8%) on apixaban. Those patients initiated on apixaban had higher mean ± SD CHA2 DS2 -VASc scores than those initiated on a VKA (3.1 ± 1.6 vs. 2.9 ± 1.6). Those initiated on dabigatran had lower mean CHA2 DS2 -VASc scores (2.7 ± 1.6) than all other groups. Patients with a history of a prior stroke were significantly more likely to be initiated on a NOAC compared with a VKA [odds ratio (OR) 1.35, 95% confidence interval (CI) 1.28-1.43]. By contrast, patients with a history of myocardial infarction were less likely to be initiated on a NOAC compared with a VKA (OR 0.72, 95% CI 0.67-0.77). Atrial fibrillation patients who were initiated on apixaban had higher stroke risk scores than patients initiated on VKAs. Interestingly, opposite results were found for dabigatran.

Gundlund A ，Staerk L ，Fosbøl EL ，Gadsbøll K ，Sindet-Pedersen C ，Bonde AN ，Gislason GH ，Olesen JB ... -  《-》