for people ages 18 years and up (full criteria)
at Oakland, California and other locations
study started
estimated completion:



Sickle cell anemia is a rare disease occurring in an estimated 66,000 children and adults, often poor and underserved, in the United States. Strokes and silent strokes contribute significantly to illness burden in adults with sickle cell anemia, resulting in impairment, challenges with school and job performance, and premature death. Five NIH studies have identified therapies to prevent overt and silent strokes in children with sickle cell anemia, including monthly blood transfusion therapy (for preventing initial and recurrent strokes) and hydroxyurea (for preventing initial strokes). However, no stroke trials have established therapeutic approaches for adults with sickle cell anemia, despite the observation that at least 99% of children with sickle cell anemia 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). Strokes in adults with sickle cell anemia have simply not been well studied. Therapies applied in children may not be effective for stroke prevention in adults with sickle cell anemia. Identifying subgroups of adults with sickle cell anemia and higher incidence coupled with the contribution of established stroke risk factors in the general population (smoking, diabetes, obesity, renal disease) will provide the prerequisite data required for the first ever phase III clinical trials focused on secondary stroke prevention in adults. In six adult sickle cell disease centers, the investigators will conduct a prospective cohort study to test the primary hypothesis that the incidence of stroke recurrence in adults with silent strokes treated with hydroxyurea will be greater than in those without strokes treated with hydroxyurea. We will test two secondary hypotheses: 1) adults with sickle cell anemia and silent strokes have cognitive deficits when compared to adults with sickle cell anemia without silent strokes; and 2) adults with sickle cell anemia and strokes receiving regular blood transfusion will have a higher incidence of stroke recurrence than adults with sickle cell anemia without strokes. We will recruit at least 72 individuals with sickle cell anemia and history of silent stroke receiving hydroxyurea therapy, at least 72 individuals with sickle cell anemia and no history of stroke, and at least 50 individuals with sickle cell anemia and history of overt stroke receiving transfusion therapy.

Official Title

The Epidemiology of Silent and Overt Strokes in Adults With Sickle Cell Anemia: a Prospective Cohort Study


Anemia, Sickle Cell Sickle Cell Disease Stroke Sickle Cell Thalassemia Sickle Cell-Beta0-Thalassemia Anemia Thalassemia


You can join if…

Open to people ages 18 years and up

  1. SCA confirmed on hemoglobin analysis or documentation of phenotype
  2. ≥ 18 years of age
  3. Followed regularly (≥ 3 clinic visits per year) in the hematology clinics and have demonstrated adherence to routine clinic visits and follow-up visits for ≥ 3 years
  4. Willing to be followed prospectively for a minimum of 3.5 years and agree to a standard care entry MRI/MRA, exit MRI/MRA, as well as MRI/MRA performed at 12 to 18 month intervals
  5. For participants with history of silent strokes: Participants with evidence of a prior cerebral infarction ≥ 3 mm in size based on MRI with ≥ 1.5T magnet
  6. For participants with history of silent strokes: no regular blood transfusion for > 6 months continuously
  7. For participants with history of silent strokes: are receiving hydroxyurea for at least six months on stable dose
  8. For participants with history of overt strokes: those receiving regular blood transfusion therapy defined as scheduled at least once every 6 weeks, with a goal to maintain HbS concentrations less than 30% for at least the first two years after the initial overt stroke, and less than 50% thereafter
  9. For participants with history of overt strokes: evidence based on neurological sequelae or MRI with at least 1.5T magnet

You CAN'T join if...

  1. Participants judged to be non-compliant by the hematologist based on previous experience in terms of clinic appointments and following medical advice
  2. Contraindications to MRI, including individuals with MRI-incompatible foreign metal objects
  3. Cirrhosis
  4. Known seropositivity for HIV
  5. End-stage renal disease (ESRD)
  6. Baseline oxygen requirement for oxygen saturation < 90% on room air due to chronic pulmonary disease
  7. Any baseline rheumatologic disease(s) associated with end-organ damage
  8. For participants with previous silent strokes: Receiving transfusion therapy


  • UCSF Benioff Children's Hospital, Oakland not yet accepting patients
    Oakland California 94609 United States
  • Washington University School of Medicine accepting new patients
    Saint Louis Missouri 63110 United States


accepting new patients
Start Date
Completion Date
Vanderbilt University Medical Center
Study Type
Last Updated