Substantial differences in initiation of antithrombotic treatment and clinical outcome among non-valvular atrial fibrillation patients treated in inpatient and outpatient settings: a nationwide cohort

Abstract

Purpose: Patients with atrial fibrillation (AF) are encountered and treated in different health care settings, which may affect the quality of care. We investigated the use of antithrombotic treatment and the risk of thromboembolism and bleeding in AF patients according to health care setting. Methods: Using national Danish registers, we categorized non-valvular AF (1997-2009) patients according to the setting of their first-time AF contact as inpatients, outpatients, or emergency department (ED) patients. Event rates and hazard ratios, calculated using Cox regression analysis, were estimated for thromboembolism and bleeding. Results: We included 147,774 non-valvular AF patients (mean age 72.4 years [SD 13.6], 52.1% males) of whom 58.8% were inpatients (mean CHA2DS2-VASc score 3.1 [SD 1.8]), 37.9% outpatients (mean CHA2DS2-VASc 2.4 [SD 1.6]) and 3.3% ED patients (mean CHA2DS2-VASc 2.3 [SD 1.7]). Warfarin treatment 90 days after AF diagnosis was 33.5%, 52.4% and 18.5%, respectively (Figure 1) (p<0.001). Initiation of antithrombotic treatment was not markedly influenced by predicted thromboembolic (CHA2DS2-VASc score) or bleeding risk (HAS-BLED score) regardless of health care setting. Inpatients experienced 4.35 (95% CI: 4.28-4.43) thromboembolic events per 100 person-years, compared to 2.61 (95% CI: 2.55-2.67) for outpatients. Relative to inpatients, outpatients had a significantly lower risk of thromboembolism (adjusted hazard ratio (HR) 0.69 [95% CI: 0.66-0.73]) and bleeding (0.75 [0.70-0.79]). ![Figure][1] Percentage claiming warfarin Conclusion: In a nationwide cohort of non-valvular AF patients, outpatients were much more likely to receive antithrombotic treatment and had a significantly lower risk of both thromboembolism and bleeding compared to inpatients. More insight is needed regarding the optimal organization of AF care. [1]: pending:yes