Sex Differences in Large Vessel Occlusion Screening and Thrombectomy Outcomes: Insights from a Population-Based Cohort Study in Ontario

Highlight

• Female patients with acute cerebral ischemia less frequently receive intracranial neurovascular imaging compared to males.
• Among imaged patients, females have a higher proportion of large vessel occlusion (LVO) than males.
• Thrombectomy utilization is comparable between sexes once LVO is identified, though overall thrombectomy use appears higher in females due to prevalence differences.
• Female patients with LVO treated with thrombectomy exhibit lower long-term mortality and a better composite outcome compared to males.

Study Background

Acute ischemic stroke caused by large vessel occlusion (LVO) represents a critical subset with severe clinical consequences and high morbidity and mortality. Timely detection and endovascular thrombectomy have significantly improved outcomes in eligible patients. However, sex-based disparities in stroke care processes and outcomes remain poorly understood. Prior studies suggest possible differences in stroke recognition, treatment access, and outcomes between females and males. Understanding these variations is vital for optimizing equitable stroke care delivery. This study aims to elucidate population-based sex differences in LVO screening, thrombectomy use, and long-term outcomes in an Ontario cohort of acute cerebral ischemia patients.

Study Design

This was a retrospective population-based cohort study leveraging the Ontario Stroke Registry linked with health administrative databases. Adult patients hospitalized for cerebral ischemia within 24 hours of last seen normal were included across two fiscal years (2019/2020 and 2022/2023). The study examined sex differences in receipt of intracranial neurovascular imaging, intravenous thrombolysis, and thrombectomy interventions. Among patients found to have LVO on imaging, long-term outcomes including mortality, hospital readmission, and nursing home admission were evaluated up to 2025 using Cox proportional hazards models, stratified by thrombectomy treatment.

Key Findings

Of 16,935 eligible patients (47% female, median age 76), females were significantly less likely than males to undergo intracranial vascular imaging (83.6% vs. 87.8%, P<0.01). Intriguingly, among those imaged, females had a higher LVO prevalence compared to males (19.3% vs. 15.9%, P<0.01), suggesting under-screening of females despite higher disease burden.

In the overall cohort, thrombectomy use was modestly higher in females (adjusted relative risk 1.08, 95% CI 1.01-1.16). However, when analyses were restricted to patients with confirmed LVO, thrombectomy utilization rates were statistically equivalent between sexes (adjusted relative risk 0.98, 95% CI 0.93-1.03). This finding implies equitable access to thrombectomy once LVO diagnosis was established.

Regarding clinical outcomes, females with LVO who received thrombectomy had a significantly lower adjusted hazard of a composite endpoint including mortality, readmission, and nursing home admission compared with males (adjusted hazard ratio 0.88, 95% CI 0.77-0.99). This suggests a potential sex-related difference in response to or recovery after thrombectomy.

Expert Commentary

This study offers valuable population-level insights into sex-related disparities in acute stroke care pathways. The lower rate of intracranial imaging in females raises concerns about potential under-recognition or implicit bias, which may delay appropriate interventions. Given the higher LVO prevalence in women who were imaged, improving screening protocols or clinical suspicion in females is warranted.

The similar thrombectomy rates once LVO is identified affirm equitable procedural treatment. Nevertheless, the improved long-term outcomes observed in females post-thrombectomy are intriguing and may reflect biological differences, varying comorbidities, or social factors influencing rehabilitation and post-discharge care.

Limitations include its retrospective design and reliance on administrative data, which may lack granularity on stroke severity, procedural details, or functional outcomes. Moreover, the study is geographically limited to Ontario, with potential implications for generalizability to differing healthcare systems.

Current stroke guidelines do not mandate sex-specific modifications for LVO screening or thrombectomy eligibility, but this study suggests that sex-aware evaluation might enhance detection rates. Further prospective research is encouraged to clarify mechanisms underpinning sex differences and inform personalized stroke management.

Conclusion

This population-based cohort study reveals notable sex differences in stroke evaluation and outcomes in Ontario. Females with acute cerebral ischemia are less frequently imaged for intracranial vessels despite a higher rate of LVO among those screened. While thrombectomy use is equitable among LVO patients, females benefit from better long-term survival and composite outcomes after intervention. These findings underscore the importance of incorporating neurovascular imaging and LVO status into future research and clinical protocols to identify and rectify sex-based disparities in stroke care and outcomes. Enhancing awareness and screening of LVO in females may improve timely treatment and stroke prognosis.

Funding and ClinicalTrials.gov

The study was supported by institutional and governmental research funds associated with the Ontario Stroke Registry. No clinical trial registration was applicable given retrospective administrative data usage.

References

1. Siddharthan YPS, Kapral MK, Fang J, et al. Sex Differences in Screening for Large Vessel Occlusion and Thrombectomy: A Population-Based Cohort Study. Stroke. 2026 Jul 10. PMID: 42427338.
2. Goyal M, Menon BK, van Zwam WH, et al. Endovascular thrombectomy after large-vessel ischaemic stroke: a meta-analysis of individual patient data from five randomised trials. Lancet. 2016;387(10029):1723-1731.
3. Baber U, Kini AS, Sharma SK, et al. Sex differences in stroke incidence, risk factors, and outcomes: A review. Stroke. 2020;51(8):2402-2409.