Incidence rates of recurrent stroke in individuals with SCD receiving hydroxyurea therapy, blood-transfusion therapy, or no therapy for secondary stroke prevention in published studies. The expected incidence rates of stroke recurrence while on regular blood-transfusion therapy, hydroxyurea (HU) therapy, or no therapy are 1.9 (95% confidence interval [CI], 1.0-2.9), 3.8 (95% CI, 1.9-5.7), and 29.1 (95% CI, 19.2-38.9) events per 100 patient years, respectively. Reprinted from Kassim et al.¹