Abstract 12: Oral Anticoagulant Prescribing For Older Adults Newly Diagnosed With Atrial Fibrillation During Hospitalization

Background: Oral anticoagulants are indicated in patients with atrial fibrillation (AF) at elevated thromboembolic risk. AF is often diagnosed during hospitalization, yet little is known about rates of anticoagulant initiation in this setting.

Methods: We examined a 20% national sample of Medicare fee-for-service beneficiaries enrolled in Part D, aged >65 years, who were hospitalized in 2016, and who received a new diagnosis of AF. The primary outcome was anticoagulant claim within 7 days of discharge home. We used multivariable logistic regression and post-estimation predicted probabilities to identify predictors of discharge with an anticoagulant, hypothesizing that thromboembolic risk, bleeding risk, and frailty would independently influence anticoagulant initiation.

Results: Among 31,889 patients diagnosed with AF while hospitalized (mean age, 78; 52% female; 84% white; 95% CHA₂DS₂-VASc ≥2; 84% HAS-BLED ≥2; 37% frail), one-quarter initiated an anticoagulant following discharge. In multivariable models, rates of anticoagulant initiation varied by primary reason for hospitalization, with the highest predicted probability of initiation among those with a primary diagnosis of AF (46.3%; 95% CI 45.1-47.5), followed by cardiac surgery (42.8%; 39.6-46.0), other cardiovascular conditions (25.1%; 24.3-26.0), non-cardiac diagnoses (18.6%; 17.3-19.9), and bleeds (3.6%; 2.3-5.0). Higher CHA₂DS₂-VASc score was associated with a small increase in anticoagulant initiation (predicted probability 19.8% [15.4-24.2] for CHA₂DS₂-VASc <2 and 25.2% [24.7-25.7] for ≥4). Higher HAS-BLED score was associated with a small decrease (25.7% [24.6-26.8] for HAS-BLED <2 and 23.4% [22.7-24.1] for ≥3). Increased frailty was associated with decreased likelihood of anticoagulant initiation, with robust and moderately-severely frail patients having predicted probabilities of 25.0% (23.3-26.6) and 17.6% (15.9-19.2) respectively.

Discussion: Anticoagulant initiation is uncommon among older adults newly diagnosed with AF during hospitalization, even among those hospitalized primarily for AF and those with high thromboembolic risk. Providers should carefully weigh risks and benefits of anticoagulants with all inpatients found to have AF.