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Published on: February 28, 2012
Comparison of 12 risk stratification schemes to predict stroke in patients with nonvalvular atrial fibrillation
Insights
Stroke risk stratification in atrial fibrillation varies significantly between schemes, leading to inconsistent anticoagulation use. Research is needed for an optimal, standardized approach to improve patient care.
Area of Science:
- Cardiology
- Neurology
- Clinical Risk Stratification
Background:
- Numerous stroke risk stratification schemes exist for nonvalvular atrial fibrillation (AF).
- Discrepancies in these schemes cause inconsistent risk estimates and variable anticoagulation practices.
Purpose of the Study:
- To analyze and compare existing stroke risk stratification schemes for nonvalvular AF.
- To evaluate the consistency and clinical relevance of stroke risk stratification in AF patients.
Main Methods:
- Analysis of twelve published stroke risk stratification schemes for nonvalvular AF.
- Comparison of predicted risk status with observed stroke rates in independent test cohorts.
Main Results:
- Schemes varied in origin (event-rate vs. consensus) and included variables (clinical vs. echocardiographic).
- Observed stroke rates differed widely across schemes, with low-risk rates from 0-2.3% and high-risk rates from 2.5-7.9% annually.
- Patient categorization varied significantly, with low-risk fractions from 9-49% and high-risk fractions from 11-77%.
Conclusions:
- Substantial clinical differences exist among current stroke risk stratification schemes for AF.
- Further research is essential to identify an optimal scheme for primary prevention.
- Standardization of recommendations is needed for uniform anticoagulation selection in AF patients.
Background And Purpose:
More than a dozen schemes for stratifying stroke risk in patients with nonvalvular atrial fibrillation have been published. Differences among these schemes lead to inconsistent stroke risk estimates for many atrial fibrillation patients, resulting in confusion among clinicians and nonuniform use of anticoagulation.
Methods:
Twelve published schemes stratifying stroke risk in patients with nonvalvular atrial fibrillation are analyzed, and observed stroke rates in independent test cohorts are compared with predicted risk status.
Results:
Seven schemes were based directly on event-rate analyses, whereas 5 resulted from expert consensus. Four considered only clinical features, whereas 7 schemes included echocardiographic variables. The number of variables per scheme ranged from 4 to 8 (median, 6). The most frequently included features were previous stroke/TIA (100% of schemes), patient age (83%), hypertension (83%), and diabetes (83%), and 8 additional variables were included in >/=1 schemes. Based on published test cohorts, all 8 tested schemes stratified stroke risk, but the absolute stroke rates varied widely. Observed rates for those categorized as low risk ranged from 0% to 2.3% per year and those categorized as high risk ranged from 2.5% to 7.9% per year. When applied to the same cohorts, the fractions of patients categorized by the different schemes as low risk varied from 9% to 49% and those categorized by the different schemes as high-risk varied from 11% to 77%.
Conclusions:
There are substantial, clinically relevant differences among published schemes designed to stratify stroke risk in patients with atrial fibrillation. Additional research to identify an optimum scheme for primary prevention and subsequent standardization of recommendations may lead to more uniform selection of patients for anticoagulant prophylaxsis.
