Stroke Prevention Over the Last 10 Years: Gender Gap Still Needs Work

Hospitalizations for stroke decreased between 2004 and 2014, in both women and men on anticoagulants for atrial fibrillation (AF). But women still suffer from stroke at higher rates than men, according to a study published online in the American Journal of Cardiology.¹

“In this 10-year time period, the addition of female gender in commonly used risk-scoring algorithms and the introduction of DOACs into clinical practice are two important changes that were introduced for stroke prevention among patients with AF. Although a causal inference cannot be drawn, it may be reasonable to hypothesize that the decreasing trend in stroke hospitalizations among anticoagulated patients with AF noted in our analysis may have been at least in part due to these two practice changes,” wrote first author Ghanshyam Palamaner Subash Shantha, MBBS, MPH, of the University of Iowa (Iowa City, IA), and colleagues.

Research suggests that women with AF are at higher risk for stroke than men, even when anticoagulated on warfarin. To account for this risk discrepancy, female gender has been included in the CHA2DS2-VASc score for stroke risk stratification. In 2005, these newer risk scores began to be more widely used in practice. About the same time, direct acting oral anticoagulants (DOACs) became available.

To see whether these changes had an impact on gender differences in stroke burden, researchers undertook a large, nationally representative study. Using data from the Nationwide Inpatient Sample, the largest all-payer database of inpatient hospitalizations in the US, they evaluated gender differences in hospitalization for stroke among patients with AF between 2005 and 2014.

Key Results

. Women with AF: 18,413,291 hospitalizations; 740,635 with stroke as primary diagnosis

. Men with AF: 18,035,866 hospitalizations; 595,730 with stroke as primary diagnosis

. Age-adjusted stroke hospitalizations significantly increased in both women and men (p_trend < 0.001)

Women: 443 per million in 2005; 495 per million in 2014

Men: 351 per million in 2005; 453 per million in 2014

. Anticoagulation Rates: Significantly increased in both women and men (p_trend < 0.001)

Women:  11.5% in 2005; 24.0% in 2014

Men: 11.7% in 2005; 24.9% in 2014

. Stroke hospitalizations involving anticoagulated patients with AF: Significantly decreased in women and men (p_trend < 0.001)

Women: 411 per million in 2005; 347 per million in 2014

Men: 402 per million in 2005; 311 per million in 2014)

The authors noted that the study cohort showed a trend toward increasing comorbidities which are also stroke risk factors, which could explain why stroke hospitalizations increased over this time period. However, the underlying explanation remains unclear.

They also emphasized that women had much more stroke hospitalizations than men. Although the explanation remains unknown, they mentioned biological reasons, such as higher systemic inflammation and higher procoagulant markers in women vs men.  Also, anticoagulation rates may be lower in women. While some studies refute this, results from this study showed that the gender gap in stroke risk narrowed among patients with AF on anticoagulants.

“This alludes to the possibility that effective anticoagulation in women may attenuate the gender gap in stroke risk,” they stressed.

The authors mentioned several limitations, including lack of data on AF type, quality of anticoagulation, and stroke severity. Also, the study could not differentiate stroke precipitated by AF vs other causes, and could not evaluate recurrent strokes.

Take Home Points

. Nationally representative study showed that stroke hospitalizations significantly increased in men and women between 2004 and 2015.

. Anticoagulation rates increased and stroke hospitalizations among anticoagulated patients decreased for both women and men over this time period

. Women still had much more stroke hospitalizations than men, but the gender gap narrowed among patients on anticoagulants

. Results suggested more effective anticoagulation among women may help close the gender gap in stroke risk

References:

1. Shantha GPS, Mentias A, Bhise V, et al. Gender Differences in the Trends of Hospitalizations for Acute Stroke Among Patients With Atrial Fibrillation in the United States: 2005 to 2014. Am J Cardiol. 2017;120:1541-1548.