Initiation of oral anticoagulation in US older adults newly diagnosed with atrial fibrillation during hospitalization

BACKGROUND: Atrial fibrillation is a common cause of stroke among older adults and is often first detected during hospitalization, given frequent use of cardiac telemetry. METHODS: In a 20% national sample of Medicare fee-for-service beneficiaries, we identified patients aged 65-or-older newly diagnosed with atrial fibrillation while hospitalized in 2016. Our primary outcome was an oral anticoagulant claim within 7-days of discharge. Multivariable logistic regression analyses assessed relationships between anticoagulation initiation and thromboembolic and bleeding risk scores while controlling for demographics, frailty, comorbidities, and hospitalization characteristics. Elevated HAS-BLED score was associated with a small decrease in probability of anticoagulant initiation (25.4% [CI, 24.4%-26.4%] for score <2 and 23.1% [CI, 22.5%-23.8%] for ≥3). Frailty was associated with decreased likelihood of oral anticoagulant initiation (24.7% [CI, 23.2%-26.2%] for non-frail and 18.1% [CI, 16.6%-19.6%] for moderately-severely frail). Anticoagulant initiation varied by primary reason for hospitalization, with predicted probability highest among patients with a primary diagnosis of atrial fibrillation (46.1% [CI, 45.0%-47.3%]) and lowest among those with non-cardiovascular conditions (13.8% [CI, 13.3%-14.3%]) and bleeds (3.6% [CI, 2.4%-4.8%]). CONCLUSIONS: Oral anticoagulant initiation is uncommon among older adults newly diagnosed with atrial fibrillation during hospitalization, even among patients hospitalized primarily for atrial fibrillation and patients with high thromboembolic risk. Clinicians should discuss risks and benefits of oral anticoagulants with all inpatients found to have atrial fibrillation.