We found that women with acute ischemic stroke were older and more commonly widowed than men, had a higher prevalence of prestroke disability, of intracranial arterial occlusions and of uncertain time of stroke onset; they also had higher admission NIHSS scores and a worse functional outcome. After adjusting for other predictors of functional outcome, female sex was still an independent predictor of poor prognosis at 6 months. Our findings are consistent with previous studies, which have shown that compared to men, women with stroke tend to be older, are less likely to emerge independent or be discharged home [3
Among our patients, women had higher NIHSS scores at presentation, but similar ischemic lesion volumes when compared to men. Their increased neurologic deficits at presentation might have been partly explained by a higher frequency of previous stroke. There were no differences in the time to first neuroimaging, or in the rates of intravenous or intra-arterial thrombolysis between men and women. Our data support previous studies that found no difference in intravenous rt-PA utilization between men and women during the treatment window [21
]. However, several other studies have reported that females are less frequently treated with intravenous rt-PA after multivariable adjustment [3
Our study is the first to report a higher prevalence of intracranial large-artery occlusion at stroke presentation in women. Despite this, ischemic lesion volumes were not different between men and women, raising interesting hypotheses concerning potential differences in collateralization and infarct growth. A recent publication showed that in patients treated with intravenous rt-PA, the frequency of residual arterial occlusion is higher in males and that women had a trend to a higher frequency of large territorial infarcts although neither ischemic lesion volume nor the rates of intracranial large-artery occlusion before thrombolysis were described [25
]. A higher recanalization rate after intravenous rt-PA in women, as well as a higher response rate to intra-arterial thrombolysis, was also described [26
]. A pooled analysis of randomized controlled trials showed a greater benefit for intravenous thrombolysis in women and nullification of the usual gender difference in outcome [28
]. The considerable frequency of intracranial occlusions and the worse prognosis of women after stroke in our patients confer even more importance to the use of recanalization therapies in females.
Our study has some limitations. First, no gold-standard tests (magnetic resonance imaging with diffusion-weighted imaging or follow-up CT scans) were used to verify ischemic lesion volumes. Nevertheless, CTA-SIs correlate with lesion volumes on diffusion-weighted imaging and may have advantages over other techniques because CTA-SIs cover the entire brain and are available at the completion of imaging [17
]. Secondly, factors not included in our analysis that could partially explain gender disparity in outcome after acute ischemic stroke include poststroke depression, degree of social support, biological effects of gender as a modulator of ischemic cell death and baseline frequency of silent brain injury (e.g. silent infarcts, white matter disease, atrophy) [29
In conclusion, women less frequently achieve independence after acute ischemic stroke independent of admission NIHSS scores, age, ischemic volume lesion, prestroke mRS, and the presence of intracranial large-vessel occlusion. A better understanding of the causes of gender disparities in ischemic stroke, including risk factors, stroke mechanisms, response to acute stroke therapies, and recovery will hopefully lead to better outcomes in both sexes in the future.