Factors Associated with Anticoagulation Delay Following New-Onset Atrial Fibrillation

Abstract

Oral anticoagulation (OAC) is effective yet reportedly underutilized for stroke prevention in atrial fibrillation (AF). Factors associated with delayed OAC after incident AF are unknown. Using a large electronic medical record, we identified incident episodes of AF diagnosed in 2006 to 2014 using a validated algorithm. Among patients with a Congestive heart failure, Hypertension, Age, Diabetes, and Stroke (CHADS₂) score ≥1 started on OAC within 1 year, we examined baseline characteristics at AF diagnosis and their association with time to OAC using multivariable Cox proportional hazards modeling. Of 4,388 patients with incident AF and CHADS₂ score ≥1 who were started on OAC within 1 year, the mean age was 72.6, and 41% were women. Median time to OAC was 5 days (interquartile range 1 to 43), and most patients received warfarin (86.3%). Among patients without prevalent stroke, 98 strokes (2.2% of the sample) occurred between AF diagnosis and OAC initiation. In multivariable analyses, several factors were associated with delayed OAC including female gender (hazard ratio [HR] 1.08, 95% confidence interval [CI] 1.01 to 1.15), absence of hypertension (HR 1.15, 95% CI 1.03 to 1.27), previous fall (HR 1.53, 95% CI 1.08 to 2.17), and chronic kidney disease (HR 1.12, 95% CI 1.04 to 1.21). Among women, OAC prescription at 1, 3, and 6 months was 70.0%, 81.7%, and 89.5%, respectively, whereas for men, OAC prescription was 73.4%, 84.0%, and 91.5%, respectively. Most patients with new AF and elevated stroke risk started on OAC receive it within 1 week, although the promptness of initiation varies. The stroke rate is substantial in the period between AF diagnosis and OAC initiation. Interventions targeting identified risk factors for delayed OAC may result in improved outcomes.