Few models had addressed the cumulative nature of risk factors where a combination of risk factors would confer a greater risk than either factor alone .
In patients at high risk of stroke , anticoagulation is cost effective , but not for those with a low risk of stroke .
The risk of stroke in atrial fibrillation ( AF ) needs to be assessed in each patient to determine the clinical and cost-effectiveness of thromboprophylaxis , with the aim of appropriate use of antithrombotic therapy .
To achieve this , stroke risk factors in AF population s need to be identified and stroke risk stratification models have been devised on the basis of these risk factors .
In this article , we firstly provide a systematic review of studies examining the attributable stroke risk of various clinical , demographic and echocardiographic patient characteristics in AF population s. Secondly , we performed a systematic review of published stroke risk stratification models , in terms of the results of the review of stroke risk factors and their ability to accurately discriminate between different levels of stroke risk .
Predictors of thromboembolism in atrial fibrillation: I. Clinical features of patients at risk. The Stroke Prevention in Atrial Fibrillation Investigators.
OBJECTIVE To identify those patients with nonrheumatic atrial fibrillation who are at high risk and those at low risk for arterial thromboembolism .  DESIGN Cohort study of patients assigned to placebo in a r and omized clinical trial . SETTING Five hundred sixty-eight in patients and out patients with nonrheumatic atrial fibrillation assigned to placebo therapy at 15 U.S. medical centers from 1987 to 1989 in the Stroke Prevention in Atrial Fibrillation study . Patients were followed for a mean of 1.3 years . MEASUREMENTS Clinical variables were assessed at study entry and correlated with subsequent ischemic stroke and systemic embolism by multivariate analysis . MAIN RESULTS Recent ( within 3 months ) congestive heart failure , a history of hypertension , and previous arterial thromboembolism were each significantly and independently associated with a substantial risk for thromboembolism ( greater than 7 % per year ; P less than or equal to 0.05 ) . The presence of these three independent clinical predictors ( recent congestive heart failure , history of hypertension , previous thromboembolism of 2.5 % per year ( no risk factors ) , 7.2 % per year ( one risk factor ) , and 17.6 % per year ( two or three risk factors ) . Nondiabetic patients without these risk factors , comprising 38 % of the cohort , had a low risk for thromboembolism ( 1.4 % per year ; 95 % Cl , 0.05 % to 3.7 % ) . Patients without clinical risk factors who were under 60 years of age had no thromboembolic events . CONCLUSION Patients with atrial fibrillation at high risk ( greater than 7 % per year ) and low risk ( less than 3 % per year ) for thromboembolism can be identified by readily available clinical variables
Few models had addressed the cumulative nature of risk factors where a combination of risk factors would confer a greater risk than either factor alone .
In patients at high risk of stroke , anticoagulation is cost effective , but not for those with a low risk of stroke .
The risk of stroke in atrial fibrillation ( AF ) needs to be assessed in each patient to determine the clinical and cost-effectiveness of thromboprophylaxis , with the aim of appropriate use of antithrombotic therapy .
To achieve this , stroke risk factors in AF population s need to be identified and stroke risk stratification models have been devised on the basis of these risk factors .
In this article , we firstly provide a systematic review of studies examining the attributable stroke risk of various clinical , demographic and echocardiographic patient characteristics in AF population s. Secondly , we performed a systematic review of published stroke risk stratification models , in terms of the results of the review of stroke risk factors and their ability to accurately discriminate between different levels of stroke risk .