Many score comparisons focus on identi cation of high risk and do not focus on low risk end of the spectrum and so are not helpful for decision-making on whether to anticoagulate. Event rates per score point varies according to study setting, ethnicity, cohort, and community vs hospitalized population, etc (as might be expected).61 Also, reported events depends on use of highly selected clinical trial cohort vs real-world unselected, and anticoagulated vs non-anticoagulated patients.62 Mortality rates from observational cohorts may also include fatal strokes as postmortems are not mandated, outcomes are nonadjudicated (as in clinical trials), and cerebral imaging is not performed. Analytical methodology matters and outcomes depend on thresholds for treatment, varying risk pro le during the study (which does not remain static), and statistical analysis Some analyses which exclude patients on anticoagulants are awed by conditioning on the future methodology, and follow-up can be dependent on continuation in a (US) health-care plan. Ethnic differences are also evident in stroke risk related to AF. In a Taiwanese cohort, the risk of stroke was 1.78% per year in patients aged 50 to 64 years and a The risk exceeds the threshold for OAC use for stroke prevention. A modi ed CHA2DS2- VASc score has been proposed, assigning one point for The modi ed CHA2DS2- VASc score performed better than the CHA2DS2-VASc score in predicting ischemic stroke assessed by c-indexes and net reclassi cation index. For patients having a modi ed CHA2DS2-VASc score of 1 (males) or 2 (females) because of the resetting of the age threshold, use of warfarin was associated with a 30% lower risk of ischemic stroke and a similar risk of ICH compared with no treatment. Net clinical bene t analyses also favored the use of warfarin in different weighted models. 