Atrial Fibrillation: Women at higher stroke risk

Patients with atrial fibrillation (AF) have a risk of stroke that is five times greater than that of the general population.  Moreover, it has previously been described that women with atrial fibrillation have a higher annual rate of stroke than men (3% vs. 1.6%).    The reasons for this remain unclear, although previous studies have suggested that women may be treated with warfarin less frequently than men.  Therefore the aim of this study was to compare the utilisation patterns of warfarin and the risk of subsequent stroke between older men and women with AF.

In this retrospective cohort study of patients with AF in Quebec, Canada, the authors investigated the risk of stroke in patients admitted to hospital with AF between 1998 and 2007.  Administrative data were linked with prescription drug claims databases.

47.2% of the cohort of 39,398 patients were male.  The authors noted that at the time of admission with AF, women tended to be older and had a higher CHADS2 score than men (1.99 vs. 1.74; P<0.001).  At 30 days after discharge, more women than men (60.6% vs 58.2%) had filled a warfarin prescription, a finding that was confirmed following adjusted analysis.  Despite good compliance with warfarin treatment in both sexes, the crude stoke incidence was higher in women than in men (2.02 per 100 person-years vs. 1.61 per 100 person-years; P<0.001), and that this difference was largely driven by the population of patients aged 75 years or older.  Multivariable regression analysis confirmed that women had a higher risk of stroke than men (adjusted HR, 1.14; P<0.001), even after adjustment for baseline comorbid conditions, the components of the CHADS2 score, and warfarin treatment.

Conclusions:

In this retrospective study, women admitted to hospital with AF were at a higher risk of stroke than men, regardless of warfarin use.

  • Tsadok MA, Jackevicius CA, Rahme E et al.  Sex Differences in Stroke Risk Among Older Patients With Recent Diagnosed Atrial Fibrillation.  JAMA 2012;307:1952-1958.