Hydroxyurea in children with sickle cell disease in a resource-poor setting: Monitoring and effects of therapy. A practical perspective.

Background: Although effectiveness of hydroxyurea (HU) in sickle cell disease is well established, unanswered questions persist about its use in African children. We determined real-life issues of acceptability, availability, and monitoring of HU use in Nigeria.
Methods: A retrospective longitudinal review of laboratory data of patients on HU was done from case files, followed by a cross-sectional survey that captured families' perception of medication and clinic adherence, laboratory tests, benefits, side effects, and acceptability.
Results: One hundred sixteen patients (1.2-17 years) received HU (mean ± SD = 18.5 ± 4.3 mg/kg/day) in 33 months. Eighty-nine had laboratory analysis. Dose escalation was the initial goal, but only 80% of patients had some form of it. Parents reported improvement in general well-being and reduction in bone pain episodes, hospital admissions, and blood transfusion. While most parents (89.5%) reported satisfaction with HU, 61% reported dissatisfaction with daily drug use, and the frequency and cost of monitoring. Sixteen percent voluntarily stopped therapy. Adherence to daily HU was 88.8%, doctor's appointments 24.5%, hematology tests 18.9%, and organ function tests 37.4%. There were no significant toxicities. Significant increases in hemoglobin, hemoglobin F and mean corpuscular volume, and reduction in absolute neutrophil count occurred despite inconsistent dose escalation.
Conclusion: HU (10-15 mg/kg/day starting dose) is safe and seems effective and acceptable to parents. Parental commitment to therapy, pre-HU education (that continues during therapy), provision of affordable HU, and subsidized laboratory tests are important considerations for initiating therapy. Special HU clinics may facilitate dose escalation and reduce frequency of monitoring. Studies are needed on feasibility of maximum tolerable dose HU protocols in sub-Saharan Africa without compromising safety.
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