Abstract 13626: Sex Differences in Risk Factors, Treatment Patterns and Clinical Outcomes of Stroke Among Patients with Atrial Fibrillation
Background: Stroke is a serious complication associated with atrial fibrillation (AF). Women with AF are at higher risk of stroke compared with men, however the reason for this is uncertain. It has been suggested that women with AF are less adequately anticoagulated than men. Objectives: The objectives of this study were to compare risk factors for stroke, patterns of treatment with warfarin, and stroke rates, between sexes, in a population of patients with AF aged ≥65 years.
Method: We conducted a retrospective population-based cohort study of patients with AF, using administrative data with linkage between prescription drug and physicians' claims and hospital discharge databases between 1999 and 2007.
Results: Patients consisted of 39,398 men (47.2%) and 44,115 women (52.8%). At AF admission, women were older, had fewer co-morbidities but a higher mean CHADS2 score (1.99 ±1.10 vs. 1.74 ± 1.13, p<0.001). In univariate analysis, women had higher rates of stroke during the whole follow up (5.8% vs. 4.3% p<0.001) with later onset after index admission (2.4 vs. 2.1 years). Warfarin prescription gradually increased with time (from 54% in 1999 to 64% in 2006), with higher usage among women than men every year. Women had higher rates of stroke even in the population of patients who were not prescribed warfarin post-discharge (6.7% vs. 4.7%, p<0.001). In multivariable Cox regression analysis, female sex was a significant independent risk factor for stroke [HR (95%CI) 1.13 (1.06, 1.21)], even after adjusting for baseline co-morbidities and warfarin treatment. The most prominent risk factor for stroke was previous stroke in both sexes. Hypertension was a significant risk factor only in men [HR (95%CI) 1.18, (1.07, 1.31)], while heart failure was not a risk factor for stroke for either sex. Warfarin was associated with decreased stroke risk in both sexes [HR (95%CI) 0.76 (0.71, 0.81)],
Conclusions: Patients with AF, irrespective of sex, are undertreated with warfarin; but women are not treated less than men. Stroke rates are higher in women compared with men, independent of risk factors and warfarin treatment. Further research must continue to explain why women with AF are at higher risk of stroke than men.
- © 2011 by American Heart Association, Inc.