Background: The meta-analysis of randomized controlled trials has illustrated that the efficacy of low-dose non-vitamin K antagonist oral anticoagulants is inferior compared with standard-dose non-vitamin K antagonist oral anticoagulants, though they are still frequently prescribed for Asian patients with non-valvular atrial fibrillation. We aimed to further investigate the efficacy and safety of low-dose non-vitamin K antagonist oral anticoagulants by carrying out a meta-analysis of all relevant randomized controlled trials and cohort studies.

Methods: Cochrane Central Register of Controlled Trials, Embase, and MEDLINE were systematically searched from the inception to September 9, 2021, for randomized controlled trials or cohorts that compared the efficacy and/or safety of low-dose non-vitamin K antagonist oral anticoagulants in Asian patients with non-valvular atrial fibrillation. The primary outcomes were stroke and major bleeding, and the secondary outcomes were mortality, intracranial hemorrhage, and gastrointestinal hemorrhage. Hazard ratios and 95% CIs were estimated using the random-effect model.

Results: Nineteen publications involving 371 574 Asian patients with non-valvular atrial fibrillation were included. Compared with standard-dose non-vitamin K antagonist oral anticoagulants, low-dose non-vitamin K antagonist oral anticoagulants showed comparable risks of stroke (hazard ratio, 1.18; 95% CI 0.98 to 1.42), major bleeding (hazard ratio, 1.00; 95% CI 0.83 to 1.21), intracranial hemorrhage (hazard ratio, 1.13; 95% CI 0.92 to 1.38), and gastrointestinal hemorrhage (hazard ratio, 1.07; 95% CI 0.87 to 1.31), though had a higher risk of mortality (hazard ratio, 1.34; 95% CI 1.05 to 1.71). Compared with warfarin, low-dose non-vitamin K antagonist oral anticoagulants were associated with lower risks of stroke (hazard ratio, 0.73; 95% CI 0.67 to 0.79), mortality (hazard ratio, 0.69; 95% CI 0.60 to 0.81), major bleeding (hazard ratio, 0.62; 95% CI 0.51 to 0.75), intracranial hemorrhage (hazard ratio, 0.48; 95% CI 0.33 to 0.69), and gastrointestinal hemorrhage (hazard ratio, 0.78; 95% CI 0.65 to 0.93).

Conclusion: Low-dose non-vitamin K antagonist oral anticoagulants were superior to warfarin, and comparable to standard-dose non-vitamin K antagonist oral anticoagulants considering risks of stroke, major bleeding, intracranial hemorrhage, and gastrointestinal hemorrhage. Further, high qualified studies are warranted.