Influence of hemoglobin E trait on the antimalarial effect of artemisinin derivatives

To determine whether hemoglobin E trait influences the antimalarial effect of artemisinin derivatives, we retrospectively compared 32 case patients with hemoglobin E trait to 32 control patients who did not have hemoglobin E, beta-thalassemia, glucose-6-phosphate dehydrogenase deficiency, or alpha-thalassemia trait on the basis of a mean corpuscular volume greater than or equal to 78 femtoliters. All patients were admitted to the Hospital for Tropical Diseases in Bangkok, Thailand, with acute falciparum malaria. Control patients were matched to case patients with hemoglobin E trait by treatment with artemisinin derivatives versus other antimalarial drugs, by ethnic group, and by parasite count. Among 38 patients treated with artemisinin derivatives, the presence of hemoglobin E trait was associated with significantly faster parasite clearance (2.9-fold; 95% confidence interval [CI], 1.4-6.3; P = .006). Among 26 patients treated only with other antimalarial drugs, hemoglobin E trait did not significantly enhance parasite clearance (hazards ratio, 1.1; 95% CI, 0.5-2.5; P = .8). Hemoglobin E trait may potentiate the antimalarial effect of artemisinin derivatives.