Impact on Outcomes of Changing Treatment Guideline Recommendations for Stroke Prevention in Atrial Fibrillation: A Nationwide Cohort Study

Objective To investigate the impact on outcomes of changing treatment guideline recommendations by comparing the proportion of patients with atrial fibrillation (AF) recommended oral anticoagulants (OACs) under the 2011 and 2014 American College of Cardiology/American Heart Association (ACC/AHA) guidelines. Patients and Methods We used the "National Health Insurance Research Database" in Taiwan, which included 354,649 patients with AF from January 1, 1996 through December 31, 2011. Patients with a CHADS₂ (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, and prior stroke or transient ischemic attack) score of 2 or more and a CHA₂DS₂-VASc (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, prior stroke or transient ischemic attack, vascular disease, age 65-74 years, female sex category) score of 2 or more were considered to have a definitive indication for receiving OACs according to the 2011 and 2014 ACC/AHA guidelines, respectively. Results The percentages of patients with AF recommended OACs increased from 69.3% (n=245,598) under the 2011 guideline to 86.7% (n=307,640) under the new 2014 guidelines, an increment of 17.5% (95% CI, 17.4-17.6). Most women with AF (94.1%) and patients older than 65 years (97.2%) would receive OACs on the basis of the 2014 guidelines. Among patients previously not being recommended OACs in older guidelines, OAC use under the new guidelines was associated with a lower risk of adverse outcomes (ischemic stroke or intracranial hemorrhage or bleeding requiring blood transfusion or mortality) with an adjusted hazard ratio of 0.89 (95% CI, 0.85-0.94). Conclusion In this nationwide cohort study, use of the 2014 guidelines led more patients with AF to receive OACs for stroke prevention, and this increased OAC use was associated with better outcomes. Better efforts to implement guidelines would lead to improved outcomes for patients with AF.