Hydroxyurea therapy in UK children with sickle cell anaemia: A single-centre experience

Introduction: Despite the demonstrated efficacy of hydroxyurea therapy, children with sickle cell anaemia in the UK are preferentially managed with supportive care or transfusion. Hydroxyurea is reserved for children with severe disease phenotype. This is in contrast to North America and other countries where hydroxyurea is widely used for children of all clinical phenotypes. The conservative UK practice may in part be due to concerns about toxicity, in particular marrow suppression with high doses, and growth in children.

Methods and results: We monitored 37 paediatric patients with sickle cell anaemia who were treated with hydroxyurea at a single UK treatment centre. Therapy was well tolerated and mild transient cytopenias were the only toxicity observed. Comparative analysis of patients receiving ≥26 mg/kg/day versus <26 mg/kg/day demonstrates increasing dose has a significant positive effect on foetal haemoglobin (Hb; 29.2% vs. 20.4%, P = 0.0151), mean cell volume (94.4 vs. 86.5, P = 0.0183) and reticulocyte count (99.66 × 10⁹ /l vs. 164.3 × 10⁹ /l, P = 0.0059). Marrow suppression was not a clinical problem with high-dose treatment, Hb 92.25 g/l versus 91.81 g/l (ns), neutrophil count 3.3 × 10⁹ /l versus 4.8 × 10⁹ /l (ns) and platelet count 232.4 × 10⁹ /l versus 302.2 × 10⁹ /l (ns). Normal growth rates were maintained in all children. Good adherence to therapy was a significant factor in reducing hospitalisations.

Conclusion: This study demonstrates the effectiveness and safety in practice of high-dose hydroxyurea as a disease-modifying therapy, which we advocate for all children with sickle cell anaemia.