Women are more likely than men to benefit from treatment with tissue plasminogen activator after an acute ischemic stroke, reported David M. Kent, M.D., of the Tufts-New England Medical Center, Boston, and his associates.
The finding arose from a pooled analysis of four randomized trials comprising 2,178 patients who suffered an acute ischemic stroke.
In the pooled analysis, men did not differ in the probability of a normal or near-normal outcome at 90 days when treated with either tissue plasminogen activator (39%) or placebo (37%). But women treated with tissue plasminogen activator (t-PA) within 6 hours of symptom onset were significantly more likely to have a normal or near-normal outcome than were women who received a placebo (41% vs. 30%).
Treatment with t-PA enabled women in the analysis to have a probability of a normal or near-normal outcome comparable with men who received t-PA (41% vs. 39%). The trials defined normal or near-normal outcome as a score of 1 or less on the modified Rankin scores (Stroke 2005;36:62-5).
Women are known to be more likely than men to have a poor outcome after an acute ischemic stroke. Women on placebo had a significantly lower probability (30%) of a normal or near-normal outcome than did men who received a placebo (37%).
The significance of t-PA treatment according to sex did not change when the investigators controlled for age, systolic blood pressure, diabetes, baseline score on the National Institute of Health Stroke Scale, the symptom onset to treatment time (OTT), the Alberta Stroke Program Early CT Score, the effects of OTT on treatment, and the interaction of diabetes and OTT.
The researchers postulated that female sex might affect the likelihood of reperfusion because of sex-based differences in coagulation and fibrinolysis and that it might affect the response of the brain to ischemia and reperfusion because of some as-yet unknown effect of estrogen, the vascular anatomy of stroke, or the particular stroke subtype.
Only 45% of the patients in the four studies combined were women despite the fact that the overall lifetime risk of stroke is higher in women than in men. A recent report suggesting that women are less likely than men to receive IV thrombolytic therapy highlights the fact that a bias toward t-PA treatment in men may result in the unintended “targeting of treatment to patients who are actually less likely to benefit from therapy (i.e., men),” the investigators said.