A subsequent review of National Institutes of Health funded studies found that only 24% of enrolled drug study populations were women.400 This lack of recruitment continues in recent trials. For example, only 20% of women were recruited in the WARCEF trial (Warfarin Versus Aspirin Use in Patients With Impaired LV Function) as recently as 2012.407 Factors that may play a role in the appar- ent underrepresentation of women in clinical trials may be sex differences in disease prevalence and age at onset in women. A systematic review of enrollment of women in trials of coronary artery disease, heart failure, arrhythmia, and primary preven- tion reported that after accounting for age- and sex-specific dif- ferences in disease prevalence, the enrollment gaps for women narrowed, ranging from 3% for primary prevention to 13% for heart failure. Stroke was not included in this analysis, how- The percentage of women enrolled in recent stroke pre- vention trials of carotid disease and antiplatelet agents ranges from 25% to 53%, with an average of 34%, which is generally below the stroke prevalence rates by sex (Tables 14 and15). CEA Versus Medical Management for Symptomatic or Asymptomatic Carotid Stenosis Differences in the anatomy of the internal carotid arter- ies and differences in the composition of plaque between women and men have fueled speculation that there may be differential risk or benefit to intervention. Compared with men, women have smaller-caliber internal carotid arteries and shorter stenotic segments.425,426 CEA is also performed less often in women, likely because of the lower incidence of high-grade symptomatic stenosis.427,428 In a retrospective cohort study at Kaiser Permanente Medical Care Plan, for the period 2003 to 2004, 299 patients were identified on the basis of a diagnosis of TIA and carotid stenosis (>70%), that is, symptomatic stenosis.427 Approximately half (47%) were women. 