The finding emerged from an analysis of 1,752 patients treated at 19 hospitals within the Taiwan Registry of Endovascular Thrombectomy for Acute Ischemic Stroke, known as TREAT-AIS, a multicenter prospective registry of endovascular thrombectomy, the standard treatment for strokes caused by a large vessel occlusion.
Endovascular thrombectomy physically removes the clot blocking a brain artery, and two frontline techniques dominate practice. The stent retriever approach deploys a mesh-like device that snares the clot before withdrawal, while contact aspiration uses a large-bore catheter placed directly against the clot to extract it by suction.
The research team included only patients with anterior circulation stroke who received frontline stent retriever or contact aspiration alone, excluding those treated with combined techniques. They first tested whether the effect of technique on outcomes differed by sex across the whole cohort, then performed sex-stratified propensity score matching, a statistical method that pairs similar patients from each treatment group to reduce the influence of differences in baseline characteristics. The primary functional yardstick was the modified Rankin Scale, a standard measure of disability after stroke, with a score of 0 to 2 indicating independent function.
The interaction test delivered the study’s central signal. In women, contact aspiration was associated with independent functional outcome with an adjusted odds ratio of 3.39 and a 95 percent confidence interval of 1.40 to 10.18. In men, the adjusted odds ratio was 0.87 with a confidence interval of 0.50 to 1.56, which crosses 1 and therefore shows no reliable association.
After 1-to-4 propensity score matching, the pattern held. Among women, independent functional outcome at three months occurred in 26.0 percent of those treated with contact aspiration versus 8.6 percent of those treated with a stent retriever, an adjusted odds ratio of 3.94 with a confidence interval of 1.11 to 14.02. Among men, the corresponding figures were 35.1 percent with contact aspiration and 38.1 percent with a stent retriever, an adjusted odds ratio of 0.73 with a confidence interval of 0.35 to 1.53, again not statistically significant. A similar nonsignificant trend appeared for ambulatory functional outcome in women, suggesting a possible but unconfirmed benefit for walking ability.
Safety results told a calmer story. Symptomatic intracranial hemorrhage, the feared bleeding complication of clot removal, and mortality were comparable between the two techniques in both sexes. In other words, the apparent advantage of contact aspiration in women did not come at the price of more bleeding or death, and neither technique appeared riskier in men.
The authors framed the work as hypothesis-generating rather than practice-changing. The registry design is observational, meaning patients and physicians chose techniques in routine care rather than by random assignment, so unmeasured differences between groups could contribute to the results even after propensity score matching. The confidence intervals, while excluding the null value for women, are wide, reflecting the limited number of patients in some subgroups. The researchers themselves state that these findings warrant validation in larger cohorts before they should guide technique selection.
The study did not establish a mechanism, and the plain-language summary accompanying the paper notes that further research is needed to understand the reasons behind the differences. What the data do establish is that the treatment effect of frontline thrombectomy strategy may differ between women and men, a conclusion the authors highlight as supporting further validation and investigation.
Women and men may differ in how they develop diseases and respond to medical treatments, and studying these differences can help researchers understand why outcomes vary between patients. This study adds to the growing evidence that women and men may respond differently to some medical treatments and underscores the importance of considering sex as a biological variable when evaluating stroke interventions.
For patients and families, the practical takeaway is cautious optimism rather than an immediate change in care. Both techniques remain established options for large vessel occlusion stroke, and the safety profile of each was similar in this registry regardless of sex. Confirming that signal in randomized or larger observational cohorts, and identifying the biological or procedural reasons behind it, is the clear next step the authors propose.
Subject of Research: Sex-based differences in functional outcomes after contact aspiration versus stent retriever thrombectomy for anterior circulation stroke
Article Title: Sex-based heterogeneity in outcomes following frontline EVT strategies for anterior circulation stroke
Article References: Chang, Y.-M., Huang, C.-Y., Lee, C.-W., Hsieh, Y.-C., Lin, C.-J., Chen, Y.-W., Lin, K.-H., Tang, C.-W., Chu, H.-J., Fu, C.-H., Chou, C.-L., Lin, C.-H., Wei, C.-Y., Yen, S.-Y., Chen, P.-L., Lin, K.-Y., Chan, L., Sung, S.-F., Lee, M., … Jeng, J.-S. (2026). Sex-based heterogeneity in outcomes following frontline EVT strategies for anterior circulation stroke. Biology of Sex Differences. https://doi.org/10.1186/s13293-026-01011-7
Image Credits: AI Generated
DOI: 10.1186/s13293-026-01011-7
Keywords: endovascular thrombectomy, contact aspiration, stent retriever, ischemic stroke, large vessel occlusion, sex differences, functional outcome, TREAT-AIS registry, propensity score matching, symptomatic intracranial hemorrhage, modified Rankin Scale, Taiwan
News Source: Cassandra Pierce. (November 4, 2026). Clot removal technique may aid stroke recovery in women but not men. Scienmag.
