Real-world comparisons of reduced-dose non-vitamin K antagonist oral anticoagulants versus warfarin in atrial fibrillation: a systematic review and meta-analysis

We performed this meta-analysis to compare the efficacy and safety of reduced-dose non-vitamin K antagonist oral anticoagulants (NOACs) versus warfarin in patients with atrial fibrillation (AF). The PubMed and Embase databases were systematically searched until July 2019 for eligible studies that comparing the effect between any reduced-dose NOAC and warfarin in patients with AF. Risk ratios (RRs) and 95% confidence intervals (CIs) were pooled by using a random-effects model. A total of 14 observational cohorts were included. Compared with warfarin use, the use of reduced-dose NOACs was associated with decreased risks of stroke or systemic embolism (RR, 0.83; 95% CI 0.74–0.93), ischemic stroke (RR, 0.87; 95% CI 0.77–0.98), major bleeding (RR, 0.71; 95% CI 0.60–0.84), intracranial hemorrhage (RR, 0.51; 95% CI 0.44–0.60), and gastrointestinal bleeding (RR, 0.72; 95% CI 0.54–0.94), but not all cause death (RR, 0.84; 95% CI 0.67–1.06). In the subgroup analyses, all NOAC users had lower or similar rates of thromboembolic and bleeding events; and the reductions in stroke or systemic embolism, all-cause death, major bleeding, and gastrointestinal bleeding were more prominent in Asians than non-Asians. In conclusion, current published data suggest that the use of reduced-dose NOACs is non-inferior to warfarin in patients with AF (in particular Asians).