Epidemiology of Silent and Overt Strokes in Sickle Cell Disease

Sickle Cell Disease (SCD) is a rare disease occurring in an estimated 100,000 individuals, often poor and underserved, in the US. Silent and overt strokes contribute significantly to morbidity in adults with SCD, resulting in functional impairment, challenges with school and job performance, and premature death. Five NIH-funded randomized controlled trials have identified therapies to prevent silent and overt strokes in children with SCD, including monthly blood transfusion therapy (for preventing initial and recurrent strokes) and hydroxyurea (for preventing initial strokes). Despite the observation that at least 99% of children with SCD in high-income countries reach adulthood, and approximately 60% of adults will experience one or more strokes (~50% with silent strokes and ~10% with overt strokes), no stroke trials have established therapeutic approaches for adults with SCD. For adults with SCD, inadequate evidence-based guidelines exist for secondary stroke prevention strategies. Applying stroke prevention strategies in children may not be effective for stroke prevention in adults with SCD, particularly given the high rate of co-morbidities. Identifying subgroups of adults with SCD and higher incidence coupled with the contribution of established stroke risk factors in the general population (smoking, diabetes, obesity, renal disease) will provide the requisite data required for the first-ever phase III clinical trials focused on secondary stroke prevention in adults.