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Risk factors for stroke in patients with nonrheumatic atrial fibrillation: a case-control study
A W Moulton1, D E Singer, J S Haas
1Division of General Internal Medicine, Rhode Island Hospital, Providence 02903.
Insights
Older age and hypertension are key risk factors for stroke in patients with nonrheumatic atrial fibrillation. Identifying these factors can help guide anticoagulant therapy decisions for stroke prevention.
Area of Science:
- Cardiology
- Neurology
- Epidemiology
Background:
- Randomized controlled trials show anticoagulant therapy is effective for stroke prevention in nonrheumatic atrial fibrillation.
- However, limited stroke events in trials hinder detailed risk factor analysis.
- Observational studies can offer valuable insights into stroke risk factors.
Purpose of the Study:
- To identify risk factors for stroke in patients with nonrheumatic atrial fibrillation.
- Utilize case-control methodology for a larger patient cohort.
- Enhance understanding of stroke etiology in this population.
Main Methods:
- Case-control study design.
- Inclusion of 134 patients with nonrheumatic atrial fibrillation and ischemic stroke.
- Comparison with 131 control patients with nonrheumatic atrial fibrillation without stroke.
Main Results:
- Cases were significantly older (78.5 vs. 74.8 years) and more likely to have hypertension (55% vs. 38%) than controls.
- Hypertension increased stroke odds by 1.91; age over 75 by 1.73.
- Combined hypertension and age over 75 yielded a 3.26 relative odds for stroke.
Conclusions:
- Age and hypertension are significant risk factors for stroke in nonrheumatic atrial fibrillation.
- These factors should be considered in decisions regarding long-term anticoagulant therapy.
- Improved risk stratification may optimize stroke prevention strategies.
Purpose:
Randomized controlled trials have demonstrated that anticoagulant therapy is very effective at preventing stroke among patients with nonrheumatic atrial fibrillation. However, these trials have reported too few strokes for powerful risk factor analysis. Observational studies may provide additional information. The purpose of this study was to identify risk factors in a larger number of patients with stroke and nonrheumatic atrial fibrillation, using case-control methodology.
Patients And Methods:
We identified all patients discharged from one hospital over an 8-year period who met our case definition of nonrheumatic atrial fibrillation and ischemic stroke (n = 134), and compared them with contemporaneous control subjects who were discharged with nonrheumatic atrial fibrillation without stroke (n = 131).
Results:
Cases and controls were similar in terms of duration of atrial fibrillation; proportion with paroxysmal atrial fibrillation; percentage with a past medical history of angina, myocardial infarction, congestive heart failure, diabetes, or smoking; and mean left atrial size. In contrast, cases were significantly older than controls (78.5 versus 74.8 years, p = 0.002) and more likely to have a history of hypertension (55% versus 38%, p = 0.0093). The relative odds for stroke was 1.91 for patients with hypertension, 1.73 for patients older than 75 years, and 3.26 for patients with both factors.
Conclusions:
Our analysis suggests that age and hypertension should be considered when deciding upon long-term anticoagulant therapy to prevent stroke in patients with nonrheumatic atrial fibrillation.