Three-year follow-up of hydroxyurea treatment in severely ill children with sickle cell disease. The French Study Group on Sickle Cell Disease.

PURPOSE: To observe the safety and efficacy of hydroxyurea (HU), a drug that stimulates fetal hemoglobin (Hb F) production, in previously severely ill children with sickle cell disease. PATIENTS AND METHODS: HU was given in an uncontrolled study to 35 children with sickle cell disease, aged from 3 to 20 years, suffering from frequent painful crises. Mean duration of treatment was 32 months (range: 12-59 months).
RESULTS: HU induced an increase in Hb F levels in all children out one; this increase was maximal after 9 months of treatment, was largely sustained thereafter, and was related to HU dose and inversely to patients' age. We also noted an apparent reduction in crisis, which occurred principally after 3 months of therapy and did not seem strictly correlated with the rise in Hb F level. No serious hematopoietic complication was observed. Growth curves and sexual development were not modified.
CONCLUSION: Our data support the efficacy of HU in reducing painful events in children with sickle cell disease. Short- and middle-term tolerances are good. Thus, we think that HU can be given to children affected by frequent and severe painful crises. We recommend, however, very cautious use of this drug, because its long-term effects in children are still unknown.