Clinical events in children who were asymptomatic at enrollment
| Adverse event . | Hydroxyurea, N = 52, patient-year = 100 . | Placebo, N = 49, patient-year = 96 . | Analysis . | |||
|---|---|---|---|---|---|---|
| Events . | Subjects . | Events . | Subjects . | Hazard ratio (95% CI)* . | P* . | |
| Pain (all events) | 61 | 30 | 128 | 31 | 1.3 (0.8, 2.1) | .35 |
| Pain alone | 31 | 17 | 46 | 24 | 1.6 (0.9, 3.0) | .14 |
| Dactylitis | 6 | 4 | 35 | 14 | 4.2 (1.4, 12.9) | .006 |
| ACS | 3 | 3 | 10 | 7 | 2.5 (0.7, 9.7) | .17 |
| Hospitalization | 80 | 31 | 149 | 43 | 1.9 (1.2, 3.0) | .006 |
| Transfusion | 11 | 6 | 27 | 14 | 2.7 (1.0, 6.9) | .04 |
| Splenomegaly | 37 | 12 | 42 | 17 | 1.6 (0.7, 3.3) | .24 |
| Splenic sequestration | 3 | 2 | 10 | 7 | 3.8 (0.8, 18.4) | .07 |
| Sepsis | 0 | 0 | 3 | 3 | ||
| Adverse event . | Hydroxyurea, N = 52, patient-year = 100 . | Placebo, N = 49, patient-year = 96 . | Analysis . | |||
|---|---|---|---|---|---|---|
| Events . | Subjects . | Events . | Subjects . | Hazard ratio (95% CI)* . | P* . | |
| Pain (all events) | 61 | 30 | 128 | 31 | 1.3 (0.8, 2.1) | .35 |
| Pain alone | 31 | 17 | 46 | 24 | 1.6 (0.9, 3.0) | .14 |
| Dactylitis | 6 | 4 | 35 | 14 | 4.2 (1.4, 12.9) | .006 |
| ACS | 3 | 3 | 10 | 7 | 2.5 (0.7, 9.7) | .17 |
| Hospitalization | 80 | 31 | 149 | 43 | 1.9 (1.2, 3.0) | .006 |
| Transfusion | 11 | 6 | 27 | 14 | 2.7 (1.0, 6.9) | .04 |
| Splenomegaly | 37 | 12 | 42 | 17 | 1.6 (0.7, 3.3) | .24 |
| Splenic sequestration | 3 | 2 | 10 | 7 | 3.8 (0.8, 18.4) | .07 |
| Sepsis | 0 | 0 | 3 | 3 | ||
ACS indicates acute chest syndrome; and CI, confidence interval.
The hazard ratio (hydroxyurea vs placebo) and 95% CI were generated from a Cox model and the P value from the log-rank life test to compare the time to first event between the 2 treatment groups.