Gender Difference in Efficacy and Safety of Nonvitamin K Antagonist Oral Anticoagulants in Patients with Nonvalvular Atrial Fibrillation or Venous Thromboembolism: A Systematic Review and a Meta-Analysis of the Literature.

INTRODUCTION: Limited information exists on gender-related differences in the safety and efficacy of non-vitamin K antagonist oral anticoagulants (NOACs). AIM OF THE STUDY: To assess the safety and efficacy of direct oral anticoagulants (DOACs)/NOACs in men and women pooling data from randomized controlled trials on the prevention of stroke and systemic embolism in patients with nonvalvular atrial fibrillation (AF) and on the acute and extended treatment of venous thromboembolism (VTE). METHODS: MEDLINE and EMBASE databases were searched up to June 2014. The efficacy outcome was defined as the prevention of stroke and systemic embolism (AF studies), or as the prevention of recurrent VTE or VTE-related death (VTE studies). The safety outcome was defined as the occurrence of major and/or clinically relevant non-major bleeding. Differences in the efficacy and safety outcomes were expressed as risk ratio (RR) with pertinent 95% confidence intervals (95% CI). RESULTS: A total of 13 studies (> 100,000 patients) were included. DOACs appeared to have a similar efficacy and safety compared with vitamin K antagonists in female and male patients treated for nonvalvular AF and acute VTE. In the extended treatment of VTE NOACs had a RR of bleeding of 4.97 (95% CI 1.06, 23.41) in males and 1.33 (95% CI 0.63, 2.83) in females compared with placebo (subgroup difference chi-square test: 2.25, p = 0.13). CONCLUSIONS: No gender-related difference in the efficacy and safety of NOACs in patients with AF or acute VTE was found. A trend toward an increased risk of bleeding in male patients as compared with female patients was detected in the extended treatment of VTE.

ABO blood group and vascular disease: an update.

It has been well known for many years that the ABO blood group has a major influence on hemostasis, through its influence on von Willebrand factor and, consequently, factor VIII plasma levels. Although the relationship between non-O blood type and the risk of venous thromboembolism is nowadays also well established, the association with arterial thrombotic events (i.e., myocardial infarction [MI] and ischemic stroke) is less well characterized. To elucidate the latter issue, we have conducted a systematic review and meta-analysis of the existing literature. After an electronic search strategy using MEDLINE and EMBASE and a manual review of abstract books of the International Society on Thrombosis and Haemostasis and of reference lists of all retrieved articles, 28 studies were finally included in our systematic review. The prevalence of non-O blood group was significantly higher in patients with MI (pooled odds ratio [OR]: 1.28, 95% confidence interval [CI]: 1.17-1.40; p < 0.001) and ischemic stroke (pooled OR: 1.17, 95% CI: 1.01-1.35; p = 0.03) than in controls. The restriction of the analysis to high quality studies only confirmed the association with MI (pooled OR: 1.17, 95% CI: 1.03-1.32) but not with ischemic stroke (pooled OR: 1.28, 95% CI: 0.94-1.74). In conclusion, the results of our meta-analysis confirm the existing literature evidence of a weak association between non-O blood group and vascular arterial thrombosis, in particular myocardial ischemia.

Relationship between ABO blood group and hemorrhage: a systematic literature review and meta-analysis.

Several studies have suggested that patients with non-O blood group have an increased risk of both venous and arterial thromboembolic events. On the contrary, the role of ABO blood group on the risk of bleeding complications remains unclear. Thus, we performed a meta-analysis of the literature with the aim of assessing this potential association. MEDLINE and Embase databases were searched from 1946 to March 2012. Studies comparing the prevalence of different ABO blood groups in bleeding patients as well as in controls without bleeding complications were potentially includible. Two reviewers independently selected studies and extracted study characteristics, quality, and outcomes. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for each trial and pooled using a random-effects model. Twenty-two studies totalling 9,468 bleeding patients and more than 450,000 controls were included. The prevalence of O blood group was significantly higher in bleeding patients than in controls, with a resulting pooled OR of 1.33 (95% CI = 1.25 to 1.42; p < 0.001). The result of this meta-analysis of a very large sample of bleeding patients and controls suggests that O blood group is a potentially important genetic risk factor for bleeding. High-quality prospective studies are warranted to confirm these preliminary findings.

Non-O blood type is the commonest genetic risk factor for VTE: results from a meta-analysis of the literature.

It is well known that the ABO blood group exerts a major influence on hemostasis, as O blood group individuals have lower von Willebrand factor and factor VIII levels than non-O blood group subjects. To evaluate the possible clinical implication of the different ABO blood groups on the risk of developing venous thromboembolism (VTE), we conducted a meta-analysis of the existing literature. After an electronic search strategy using Medline and Embase and a manual review of abstract books of the International Society on Thrombosis and Haemostasis and of reference lists of all retrieved articles, we included in the systematic review 38 studies with 10,305 VTE cases. The prevalence of non-O blood group was significantly higher in VTE patients compared with controls with a resulting pooled odds ratio (OR) of 2.09 (95% confidence interval [CI], 1.83, 2.38; p < 0.00001). Similar findings were obtained when the genotypes A1O/BO/A2B (OR 1.73, 95% CI, 1.47, 2.05; p < 0.00001) and A1B/A1A1/BB (OR 1.87, 95% CI, 1.84, 2.44; p < 0.00001) were analyzed. The maximum VTE risk was observed in non-O-factor V Leiden patients (OR 7.60, 95% CI, 3.21, 17.99), while for G20210A prothrombin mutation it was not possible to perform a pooled analysis due to a paucity of published studies. Finally, the association between non-O blood group and VTE was weaker when provoked VTE cases were considered (OR 1.33, 95% CI, 1.18, 1.50), while it was substantially unchanged when unprovoked VTE cases were analyzed (OR 1.88, 95% CI, 1.42, 2.50). In conclusion, considering its prevalence, non-O blood group is a candidate to be one of the most important genetic risk factors for venous thrombosis.