source: Blood

year: 2017

authors: Opoka R.O, Ndugwa C.M, Latham T.S, Lane A, Hume H.A, Kasirye P, Hodges J.S, Ware R.E, John C.C

Hydroxyurea treatment is recommended for children with sickle cell anemia (SCA) living in high-resource malaria-free regions, but its safety and efficacy in malaria-endemic sub-Saharan Africa, where the greatest sickle cell burden exists, remain unknown. In vitro studies suggest hydroxyurea could increase malaria severity, and hydroxyurea-associated neutropenia could worsen infections. NOHARM was a randomized, double-blinded, placebo-controlled trial conducted in malaria-endemic Uganda, comparing hydroxyurea to placebo at 20 ± 2.5 mg/kg/day for 12 months. The primary outcome was incidence of clinical malaria. Secondary outcomes included SCA-related adverse events, clinical and laboratory effects, and hematological toxicities. Children received either hydroxyurea (N=104) or placebo (N=103). Malaria incidence did not differ between children on hydroxyurea [0.05 episodes/child/year, 95% CI (0.02, 0.13)] versus placebo [0.07 episodes/child/year (0.03, 0.16)]; the hydroxyurea/placebo malaria incidence rate ratio was 0.7 [(0.2, 2.7), p=0.61].

Time to infection also did not differ significantly between treatment arms. A composite SCA-related clinical outcome (vaso-occlusive painful crisis, dactylitis, acute chest syndrome, splenic sequestration, or blood transfusion) was less frequent with hydroxyurea (45%) than placebo (69%, p=0.001). Children receiving hydroxyurea had significantly increased hemoglobin concentration and fetal hemoglobin, with decreased leukocytes and reticulocytes. Serious adverse events, sepsis episodes, and dose-limiting toxicities were similar between treatment arms. Three deaths occurred (two hydroxyurea, one placebo, none from malaria). Hydroxyurea treatment appears safe for children with SCA living in malaria-endemic sub-Saharan Africa, without increased severe malaria, infections, or adverse events. Hydroxyurea provides SCA-related laboratory and clinical efficacy, but optimal dosing and monitoring regimens for Africa remain undefined.

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