Table 1.
Demographic and medical characteristics of sample
| SCD | Controls | p | |
|---|---|---|---|
| n=84 | n=168 | ||
|
| |||
| Frequency (%) | Frequency (%) | ||
|
| |||
| Sex | NA | ||
| Female | 45 (53.57%) | 90 (53.57%) | |
| Male | 39 (46.43%) | 78 (46.43%) | |
|
| |||
| Race | NA | ||
| African American | 82 (98.80%) | 168 (98.80%) | |
| White | 1 (1.20%) | 2 (1.20%) | |
|
| |||
| Parent Education | NA | ||
| Less than HS | 7 (8.43%) | 12 (7.14%) | |
| HS Diploma | 18 (21.69%) | 34 (20.24%) | |
| Some college | 42 (50.60%) | 76 (45.24%) | |
| College degree or higher | 16 (19.28%) | 46 (27.38%) | |
|
| |||
| Sickle Cell Disease Genotype | --- | ||
| Hb SS/HbSβ0-thalassemia | 52 (61.90%) | -- | |
| Hb SC/HbSβ+-thalassemia/ Other | 32 (38.10%) | -- | |
|
| |||
| History of chronic blood transfusion | 4 (4.76%) | -- | -- |
|
| |||
| Hydroxyurea treatment history a | 43 (51.19%) | -- | -- |
|
| |||
| History of overt stroke b | 2 (2.38%) | -- | -- |
|
| |||
| History of conditional or abnormal TCD c | 12 (23.08%) | -- | -- |
|
| |||
| Mean (SD) | Mean (SD) | ||
|
| |||
| Age at evaluation (years) | 4.53 (0.38) | 4.44 (0.65) | 0.151 |
|
| |||
| SIB-R Early Development Index | 108.62 (18.30) | 108.68 (16.50) | 0.980 |
|
| |||
| Duration of hydroxyurea treatment (months) | 23.95 (14.18) | -- | -- |
|
| |||
| Hemoglobin (g/dL) | 9.92 (1.34) | -- | -- |
|
| |||
| WBC (x10e3/mm3) | 10.04 (3.22) | -- | -- |
|
| |||
| Fetal hemoglobin (%) | 23.79 (10.59) | -- | -- |
|
| |||
| Hemoglobin oxygen saturation, (%) | 99.23 (0.81) | -- | -- |
M, mean; SD, standard deviation; n, sample size; %, percent; SIB-R, Scales of Independent Behavior – Revised; TCD, transcranial doppler; WBC, white blood cell count;
P-values are based on two-sample t-tests. Patient characteristics (sex, race and parent education) used for matching are not subject to statistical testing comparing between SCD patients and controls. These values are presented in the table solely for demographic information. Hematologic indices were the average value of measurements collected within 3 months of or the one closest to neurocognitive assessment.
Ever treated with hydroxyurea therapy
Due to the limited number of cases, we did not assess group differences based on history of overt stroke
Only performed on patients with Hb SS/HbSβ0-thalassemia. TCD mean flow velocity values for each artery: normal (< 170 cm per second) and conditional/abnormal (≥ 170 cm per second).