2 Stroke October 2017 population-based study of incidence and outcome of TIA and stroke ( OXVASC [ Oxford

Many studies have reported greater stroke severity and worse outcome in women albeit with some conflicting results. Potential explanations for these inconsistencies include different source populations, lack of statistical power, and methodological limitations. First, age difference at the time of stroke, if not properly accounted for, may lead to finding a spurious worse outcome in women. Second, another potential confounding factor often overlooked is functional status before the index stroke, which may influence stroke severity and prognosis even after adjustment for age. Disentangling the respective effect of sex, age, and prior handicap is important because it would shift the focus from sex differences to age-related differences in outcomes. In this respect, the properties of the modified Rankin Scale (mRS), the commonly used measure of handicap in stroke research, may also impact the observed sex differences. Finally, most previous studies did not include the full spectrum of symptomatic ischemic cerebrovascular events, particularly transient ischemic attack (TIA) and minor stroke and also pre-hospital deaths and severe strokes in community institutions. Only by including the full range of event severity can analyses reliably address sex differences in severity outcomes. To our knowledge, no published study has met these 3 conditions. Our objective was, therefore, to assess potential sex differences in the severity and prognosis of ischemic stroke/TIA between men and women in a large prospective Background and Purpose—Several studies have reported unexplained worse outcomes after stroke in women but none included the full spectrum of symptomatic ischemic cerebrovascular events while adjusting for prior handicap. Methods—Using a prospective population-based incident cohort of all transient ischemic attack/stroke (OXVASC [Oxford Vascular Study]) recruited between April 2002 and March 2014, we compared pre-morbid and post-event modified Rankin Scale score (mRS) in women and men and change in mRS score 1 month, 6 months, 1 year, and 5 years after stroke. Baseline stroke-related neurological impairment was measured with the National Institutes of Health Stroke Scale. Results—Among 2553 patients (50.6% women) with a first transient ischemic attack/ischemic stroke, women had a worse handicap 1 month after ischemic stroke (age-adjusted odds ratio for mRS score, 1.35; 95% confidence interval, 1.12– 1.63). However, women also had a higher pre-morbid mRS score compared with men (age-adjusted odds ratio, 1.58; 95% confidence interval, 1.36–1.84). There was no difference in stroke severity when adjusting for age and pre-morbid mRS (odds ratio, 1.10; 95% confidence interval, 0.90–1.35) and no difference in the pre-/post-stroke change in mRS at 1 month (age-adjusted odds ratio, 1.00; 95% confidence interval, 0.82–1.21), 6 months, 1 year, and 5 years. Women had a lower mortality rate, and there was no sex difference in risk of recurrent stroke. Conclusions—We found no evidence of a worse outcome of stroke in women when adjusting for age and pre-morbid mRS. Failure to account for sex differences in pre-morbid handicap could explain contradictory findings in previous studies. Properties of the mRS may also contribute to these inconsistencies. (Stroke. 2017;48:00-00. DOI: 10.1161/ STROKEAHA.117.018187.)