Stage 1 Registered Report: sex differences in anticoagulation and stroke outcomes among patients with atrial fibrillation: a registry-based cohort study

Women with atrial fibrillation have a higher risk of ischemic stroke and worse functional outcomes than men but may be less likely to receive adequate anticoagulation. Preliminary single-center findings in patients treated with endovascular thrombectomy for large vessel occlusion suggest that women may be under-anticoagulated prior to stroke onset. This Stage 1 Registered Report outlines a pre-specified analysis plan to test sex-based differences in anticoagulation, stroke characteristics, treatment, and outcomes in a prespecified confirmatory population and to explore whether similar patterns are observed at the national level. Using a retrospective cohort design, we will analyse local data from Stavanger University Hospital (2009–2022) and national data from the Norwegian Stroke Registry. Confirmatory analyses will include patients with atrialfibrillation and large vessel occlusion treated with endovascular thrombectomy. Sex differences in anticoagulation, stroke severity, treatments, and outcomes will be examined using chi-square tests and prespecified regression models; equivalence testing will be applied where appropriate. Exploratory analyses will assess age, comorbidity, and healthcare delivery as potential mediators and moderators. No confirmatory analyses have been conducted.