| 1. Ages 3 to 9 y (inclusive) at enrollment |
| 2. Confirmed laboratory diagnosis of HbSS or HbS-B0 thalassemia (available within 1 wk of enrollment) |
| 3. Hb ≥ 6.0 g/dL |
| 4. No history of HU use for >6 mo |
| 5. Not acutely ill at enrollment: fever, respiratory infection, sickle crisis within the previous 2 wk, or blood transfusion within the past 90 d (temporary exclusion criteria) |
| 6. Had attended the Mulago Hospital SCA clinic ≥2 times in the previous 4 y, or ≥1 time in the previous 2 y if age ≥2 y (to help ensure attendance of study visits) |
| 7. Parent and child are able to speak and understand English or Luganda (a predominant language in Kampala) |
| 8. No history of neurological abnormality known before the age of 4 mo (to avoid early non-SCA brain injury) |
| 9. Child was not currently enrolled in a clinical intervention trial |
| 10. Child and parent/legal guardian were willing to participate (if child was ≥8 y of age for assenting) |
| 11. Absence of previous stroke by standardized stroke-focused PedNIHSS examination by a study physician∗ |
| 1. Ages 3 to 9 y (inclusive) at enrollment |
| 2. Confirmed laboratory diagnosis of HbSS or HbS-B0 thalassemia (available within 1 wk of enrollment) |
| 3. Hb ≥ 6.0 g/dL |
| 4. No history of HU use for >6 mo |
| 5. Not acutely ill at enrollment: fever, respiratory infection, sickle crisis within the previous 2 wk, or blood transfusion within the past 90 d (temporary exclusion criteria) |
| 6. Had attended the Mulago Hospital SCA clinic ≥2 times in the previous 4 y, or ≥1 time in the previous 2 y if age ≥2 y (to help ensure attendance of study visits) |
| 7. Parent and child are able to speak and understand English or Luganda (a predominant language in Kampala) |
| 8. No history of neurological abnormality known before the age of 4 mo (to avoid early non-SCA brain injury) |
| 9. Child was not currently enrolled in a clinical intervention trial |
| 10. Child and parent/legal guardian were willing to participate (if child was ≥8 y of age for assenting) |
| 11. Absence of previous stroke by standardized stroke-focused PedNIHSS examination by a study physician∗ |
HbS-B0, compound heterozygote HbS and Hb Beta0 thalassemia; HbSS, homozygous HbS.
Pediatric National Institutes of Health Stroke Scale.13