Table 1.

Participant Demographic and Clinical Characteristics

Characteristics	All participants n=45	Lower hydroxyurea exposure n=22	Higher hydroxyurea exposure n=23	p-value
Study site, n (%)
NCH	29 (64.4)	13 (59.1)	16 (69.6)	0.46
LCH	16 (35.6)	9 (40.9)	7 (30.4)
Age, median (range)	12 (2 – 19)	12 (2 – 19)	11 (2 – 18)	0.20
Age group, years n (%)
<10	15 (33.3)	7 (31.8)	8 (34.8)
10–17	25 (55.6)	11 (50.0)	14 (60.9)	0.43
≥18	5 (11.1)	4 (18.2)	1 (4.3)
Males, n (%)	25 (55.6)	13 (59.1)	12 (52.2)	0.64
Race, n (%)
Black	44 (97.8)	22 (100)	22 (95.7)	0.99
Other	1 (2.2)	0 (0)	1 (4.3)
Ethnicity, n (%)
Non-Hispanic	44 (97.8)	22 (100)	22 (95.7)	0.99
Hispanic/Latino	1 (2.2)	0 (0)	1 (4.3)
Genotype, n (%)
Hemoglobin SS	45 (100)	22 (100)	23 (100)	n/a
Insurance type, n (%)
Private	12 (26.7)	7 (31.8)	5 (21.7)
Public/Medicaid	18 (40.0)	9 (40.9)	9 (39.1)	0.63
Other	15 (33.3)	6 (27.3)	9 (39.1)
Duration of hydroxyurea use prior to study entry, n (%)
6–12 months	13 (28.9)	7 (31.8)	6 (26.1)	0.68
>12 months	32 (71.1)	15 (68.2)	17 (73.9)

Nationwide Children’s Hospital (NCH); Ann & Robert H. Lurie Children’s Hospital (LCH)

Participants with lower hydroxyurea exposure had a calculated hydroxyurea exposure of ≤20mg/kg/day during their intervention period;

Participants with higher hydroxyurea exposure had a calculated exposure >20mg/kg/day during their intervention period.

P-value < 0.05 was statistically significant (highlighted in bold)