Baseline characteristics of the SPRING trial participants (n = 431) in the therapy (n = 220) and comparison groups (n = 211)
| Characteristics∗ . | Combined population (n = 431) . | Therapy group (n = 220) . | Comparison group (n = 211) . | P value† . |
|---|---|---|---|---|
| Age at enrollment, y | 7.7 (6.0-10.0) | 7.2 (5.5-8.9) | 8.4 (6.4-10.7) | <.001 |
| Female sex | 224 (52.0) | 114 (51.8) | 110 (52.1) | .948 |
| Follow-up time (y), median (IQR) | 2.6 (2.0-3.0) | 2.4 (2.0-2.8) | 2.8 (1.5-3.1) | .004 |
| Transcranial Doppler velocity at screening, cm/sec | 200.0 (131.0-207.0) | 206.5 (203.0-221.0) | 130.0 (115.0-146.0) | <.001 |
| Total hemoglobin, g/dL | 7.3 (6.6-8.1) | 7.1 (6.5-7.6) | 7.7 (6.8-8.4) | <.001 |
| Height (cm) | 117.5 (109.5-126.0) | 114.5 (107.0-123.0) | 121.5 (11.5-131.0) | <.001 |
| Weight (kg) | 18.0 (16.0-22.0) | 17.0 (15.0-20.0) | 20.0 (16.0-24.0) | <.001 |
| BMI (kg/m2) | 13.5 (12.6-14.5) | 13.4 (12.7-14.3) | 13.5 (12.6-14.7) | .280 |
| Height-for-age z score, mean (SD) | −1.5 (1.3) | −1.5 (1.3) | −1.4 (1.3) | .320 |
| Weight-for-age z score, mean (SD) | −2.1 (1.1) | −2.2 (1.0) | −2.1 (1.1) | .432 |
| BMI z score, WHO standard, mean (SD) | −1.8 (1.2) | −1.8 (1.2) | −1.9 (1.3) | .385 |
| Characteristics∗ . | Combined population (n = 431) . | Therapy group (n = 220) . | Comparison group (n = 211) . | P value† . |
|---|---|---|---|---|
| Age at enrollment, y | 7.7 (6.0-10.0) | 7.2 (5.5-8.9) | 8.4 (6.4-10.7) | <.001 |
| Female sex | 224 (52.0) | 114 (51.8) | 110 (52.1) | .948 |
| Follow-up time (y), median (IQR) | 2.6 (2.0-3.0) | 2.4 (2.0-2.8) | 2.8 (1.5-3.1) | .004 |
| Transcranial Doppler velocity at screening, cm/sec | 200.0 (131.0-207.0) | 206.5 (203.0-221.0) | 130.0 (115.0-146.0) | <.001 |
| Total hemoglobin, g/dL | 7.3 (6.6-8.1) | 7.1 (6.5-7.6) | 7.7 (6.8-8.4) | <.001 |
| Height (cm) | 117.5 (109.5-126.0) | 114.5 (107.0-123.0) | 121.5 (11.5-131.0) | <.001 |
| Weight (kg) | 18.0 (16.0-22.0) | 17.0 (15.0-20.0) | 20.0 (16.0-24.0) | <.001 |
| BMI (kg/m2) | 13.5 (12.6-14.5) | 13.4 (12.7-14.3) | 13.5 (12.6-14.7) | .280 |
| Height-for-age z score, mean (SD) | −1.5 (1.3) | −1.5 (1.3) | −1.4 (1.3) | .320 |
| Weight-for-age z score, mean (SD) | −2.1 (1.1) | −2.2 (1.0) | −2.1 (1.1) | .432 |
| BMI z score, WHO standard, mean (SD) | −1.8 (1.2) | −1.8 (1.2) | −1.9 (1.3) | .385 |
IQR, interquartile range; SD, standard deviation.
The therapy group comprised of children with abnormal transcranial Doppler velocities on hydroxyurea therapy, and the comparison group was children with nonelevated transcranial Doppler velocities.
IQR, interquartile range; SD, standard deviation.
Median (IQR) for continuous variables and counts (percentages) for categorical variables unless otherwise noted.
χ2 test for counts, t test for means, and Mann-Whitney U test for medians between the therapy and comparison group.