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Estimating Bilateral Atrial Function by Cardiovascular Magnetic Resonance Feature Tracking in Patients with Paroxysmal Atrial Fibrillation
Published on: July 20, 2022
Methodologic Differences Across Studies of Patients With Atrial Fibrillation Lead to Varying Estimates of Stroke Risk
Gene R Quinn1,2,3, Olivia N Severdija2,4, Yuchiao Chang2,5
1Smith Center for Outcomes Research, Division of Cardiology, Beth Israel Deaconess Medical Center, Boston, MA.
Insights
Stroke rates in atrial fibrillation (AF) studies vary due to inconsistent methodologies. Standardizing how AF cohorts are assembled and analyzed is crucial for accurate stroke risk assessment and improved anticoagulation guidelines.
Area of Science:
- Cardiology
- Epidemiology
- Health Services Research
Background:
- Anticoagulation guidelines for atrial fibrillation (AF) rely on stroke risk scores assuming fixed stroke rates.
- Observed stroke rates in AF cohort studies exhibit significant variability, even within the same country.
- The underlying reasons for this wide variation in reported stroke rates remain unclear.
Purpose of the Study:
- To compare methodologies used in assembling and analyzing large atrial fibrillation (AF) cohorts globally.
- To assess potential biases in the estimation of stroke rates across different AF studies.
- To identify factors contributing to the variability in reported stroke rates in AF patient populations.
Main Methods:
- Systematic review of atrial fibrillation (AF) cohort studies with at least 5000 patients.
- Analysis of study methodologies for generating ischemic stroke rates off anticoagulants.
- Structured inventory of database interrogation methods and outcome validation processes.
Main Results:
- Nine studies (497,578 patients) were analyzed, with stroke rates ranging from 0.45% to 7.03% annually.
- Higher stroke rates were associated with identifying AF in inpatients versus outpatients and lack of clinical outcome validation.
- European studies reported over 4-fold higher rates than North American studies, with significant variation in International Classification of Diseases (ICD) coding.
Conclusions:
- Methodological differences in cohort composition, assembly, feature/outcome determination, and analysis strongly influence reported stroke rates in AF studies.
- The study underscores the critical need for standardized and validated methodologies in AF cohort assembly and analysis.
- Accurate stroke rate generation is essential for refining anticoagulation guidelines for patients with atrial fibrillation (AF).
Background:
Guidelines for anticoagulation in atrial fibrillation (AF) assume that stroke risk scheme point scores correspond to fixed stroke rates. However, reported stroke rates vary widely across AF cohort studies, including studies from the same country. Reasons for this variation are unclear. This study compares methodologies used to assemble and analyze large AF cohorts worldwide and assesses potential bias in estimating stroke rates.
Methods And Results:
From a previous systematic review of AF cohorts, we analyzed studies including at least 5000 patients. We assessed methods used to generate rates of ischemic stroke off anticoagulants, according to a structured inventory of database interrogation methods. Nine studies (497 578 total patients) met our criteria. Overall cohort stroke rates ranged from 0.45% to 7.03% per year. In bivariate study-level analysis, multiple features were associated with higher stroke rates, including AF identified as inpatients versus outpatients (rate ratio 2.60, 95% confidence interval, 1.19, 5.68), and lack of clinical validation of outcome events (rate ratio 4.09, 95% confidence interval, 1.06, 15.70). European studies reported rates more than 4-fold higher than North American studies. International Classification of Diseases (ICD) coding schemes for outcomes varied widely. Multiple high rate features coexisted in the same studies.
Conclusions:
Among AF cohort studies, differences in the composition, method of assembly, determination of clinical features and outcomes, and analytic approach were strongly associated with reported stroke rates. Our study highlights the need for standardized and validated methodologies for AF cohort assembly and analysis to generate accurate stroke rates to better support anticoagulation guidelines for patients with AF.
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