Validation of the Risk Estimator Decision Aid for Atrial Fibrillation (RED-AF) for predicting 30-day adverse events in emergency department patients with atrial fibrillation

Study objective: In the United States, nearly 70% of emergency department (ED) visits for atrial fibrillation result in hospitalization. The incidence of serious 30-day adverse events after an ED evaluation for atrial fibrillation remains low. This study's goal was to prospectively validate our previously reported Risk Estimator Decision Aid for Atrial Fibrillation (RED-AF) model for estimating a patient's risk of experiencing a 30-day adverse event.

Methods: This was a prospective cohort study, which enrolled a convenience sample of ED patients presenting with atrial fibrillation. RED-AF, previously derived from a retrospective cohort of 832 patients, assigns points according to age, sex, coexisting disease (eg, heart failure, hypertension, chronic obstructive pulmonary disease), smoking, home medications (eg, β-blocker, diuretic), physical examination findings (eg, dyspnea, palpitations, peripheral edema), and adequacy of ED ventricular rate control. Primary outcome was occurrence of greater than or equal to 1 atrial fibrillation-related adverse outcome (ED visits, rehospitalization, cardiovascular complications, death) within 30 days. We identified a clinically relevant threshold and measured RED-AF's performance in this prospective cohort, assessing its calibration, discrimination, and diagnostic accuracy.

Results: The study enrolled 497 patients between June 2010 and February 2013. Of these, 120 (24%) had greater than or equal to 1 adverse event within 30 days. A RED-AF score of 87 was identified as an optimal threshold, resulting in sensitivity and specificity of 96% (95% confidence interval [CI] 91% to 98%) and 19% (95% CI 15% to 23%), respectively. Positive and negative predictive values were 27% (95% CI 23% to 32%) and 93% (95% CI 85% to 97%), respectively. The c statistic for RED-AF was 0.65 (95% CI 0.59 to 0.71).

Conclusion: In this separate validation cohort, RED-AF performed moderately well and similar to the original derivation cohort for identifying the risk of short-term atrial fibrillation-related adverse events in ED patients receiving a diagnosis of atrial fibrillation.