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 .
Anticoagulation therapy for stroke prevention in atrial fibrillation: how well do randomized trials translate into clinical practice?
CONTEXT Warfarin has been shown to be highly efficacious for preventing  thromboembolism in atrial fibrillation in r and omized trials , but its effectiveness and safety in clinical practice is less clear . OBJECTIVE To evaluate the effect of warfarin on risk of thromboembolism , hemorrhage , and death in atrial fibrillation within a usual care setting . DESIGN Cohort study assembled between July 1 , 1996 , and December 31 , 1997 , and followed up through August 31 , 1999 . SETTING Large integrated health care system in Northern California . PATIENTS Of 13,559 adults with nonvalvular atrial fibrillation , 11,526 were studied , 43 % of whom were women , mean age 71 years , with no known contraindications to anticoagulation at baseline . MAIN OUTCOMES Ischemic stroke , peripheral embolism , hemorrhage , and death according to warfarin use and comorbidity status , as determined by automated data bases , review of medical records , and state mortality files . RESULTS Among 11,526 patients , 397 incident thromboembolic events ( 372 ischemic strokes , 25 peripheral embolism ) occurred during 25,341 person-years of follow-up , and warfarin therapy was associated with a 51 % ( 95 % confidence interval [ CI ] , 39%-60 % ) lower risk of thromboembolism compared with no warfarin therapy ( either no antithrombotic therapy or aspirin ) after adjusting for potential confounders and likelihood of receiving warfarin . Warfarin was effective in reducing thromboembolic risk in the presence or absence of risk factors for stroke . A nested case-control analysis estimated a 64 % reduction in odds of thromboembolism with warfarin compared with no antithrombotic therapy . Warfarin was also associated with a reduced risk of all-cause mortality ( adjusted hazard ratio , 0.69 ; 95 % CI , 0.61 - 0.77 ) . Intracranial hemorrhage was uncommon , but the rate was moderately higher among those taking vs those not taking warfarin ( 0.46 vs 0.23 per 100 person-years , respectively ; P = .003 , adjusted hazard ratio , 1.97 ; 95 % CI , 1.24 - 3.13 ) . However , warfarin therapy was not associated with an increased adjusted risk of nonintracranial major hemorrhage . The effects of warfarin were similar when patients with contraindications at baseline were analyzed separately or combined with those without contraindications ( total cohort of 13,559 ) . CONCLUSIONS Warfarin is very effective for preventing ischemic stroke in patients with atrial fibrillation in clinical practice while the absolute increase in the risk of intracranial hemorrhage is small . Results of r and omized trials of anticoagulation translate well into clinical care for patients with atrial fibrillation
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 .