Real-world or observational data are generally insuf cient to guide selection of individual anticoagulant drugs. Therefore, observational data are best used to reaf rm that real-world effectiveness is concordant with clinical trial ef cacy, based on both quality of care and generalizability.126 A meta-analysis of real-world observational studies of dabigatran was consistent with ndings from Randomized Evaluation of Long-term Anticoagulant Therapy with Dabigatran Etexilate (RE-LY). Compared with VKA, risk of stroke with dabigatran vs warfarin was Dabigatran was also associated with a lower risk of intracranial bleeding (HR, 0.45; 95% CI, 0.38-0.52) and lower risk of death (HR, 0.73; 95% CI, 0.61-0.87). Risk of gastrointestinal bleeding was higher. One systematic review and meta-analysis provided comparative effectiveness and safety data for rivaroxaban vs dabigatran (n 3 trials), rivaroxaban vs warfarin (n 11 trials), or both (n 3 trials) for stroke prevention in AF.128 Overall, the risks of stroke/ systemic thromboembolism with rivaroxaban were similar compared with dabigatran but were signi cantly reduced when compared with warfarin (HR, 0.75; 95% CI, 0.64-0.85). Major bleeding risk was signi cantly higher with rivaroxaban vs dabigatran (HR, 1.38; 95% CI, 1.27-1.49) but similar to warfarin (HR, 0.99; 95% CI, 0.91-1.07). Rivaroxaban was associated with increased all-cause mortality and gastrointestinal bleeding but similar risk of acute MI and ICH compared with dabigatran. When compared with warfarin, rivaroxaban was associated with similar risk of any bleeding, mortality, and acute MI but a higher risk of gastrointestinal bleeding and lower risk of ICH. 