Efficacy of artesunate plus amodiaquine versus that of artemether- lumefantrine for the treatment of uncomplicated childhood Plasmodium falciparum malaria in Zanzibar, Tanzania

Background. This is the first clinical trial comparing the efficacy of artesunate plus amodiaquine (ASAQ) and artemether-lumefantrine (AL)-the major artemisinin-based combination therapy (ACT) candidates for treatment of malaria in Africa-that involved an extended, 42-day follow-up period, polymerase chain reaction-adjusted parasitological cure rates (PCR APCRs), and systematic analyses of genetic markers related to quinoline resistance. Methods. A total of 408 children with uncomplicated Plasmodium falciparum malaria in Zanzibar, Tanzania, were enrolled. Children who were 6-8 months of age and/or who weighed 6-8 kg were assigned to receive ASAQ for 3 days. Children who were 9-59 months of age and who weighted ≥9 kg were randomly assigned to receive either ASAQ or AL for 3 days in standard doses. Intention-to-treat analyses were performed. Results. Age- and weight-adjusted PCR-APCRs by follow-up day 42 were 91% (188 of 206 patients) in the ASAQ group and 94% (185 of 197 patients) in the AL group (odds ratio [OR] for the likelihood of cure, 2.07; 95% confidence interval [CI], 0.84-5.10; P = .115). A total of 5 and 7 recrudescences occurred after day 28 in the ASAQ and AL groups, respectively. On the assumption that 10 malaria episodes with uncertain PCR results were recrudescences, PCR-APCRs decreased to 88% in the ASAQ group and to 92% in the AL group. Unadjusted cure rates by day 42 were 56% (116 of 206 patients) in the ASAQ group versus 77% (151 of 197 patients) in the AL group (OR, 2.55; 95% CI, 1.66-3.91; P < .001). Rates of reinfection by day 42 were 36% (65 of 181 patients) in the ASAQ arm versus 17% (31 of 182 patients) in the AL arm (OR, 0.37; 95% CI, 0.22-0.60; P < .001). A significant selection of P. falciparum multidrug resistance gene 1 allele 86N was found in isolates associated with reinfection after AL treatment, compared with isolates at baseline (2.2-fold increase; P < .001). Conclusions. Both treatments were highly efficacious, but AL provided stronger prevention against reinfection. The high proportion of recrudescences found after day 28 and the genetic selection by the long-acting partner drug underlines the importance of long follow-up periods in clinical trials. A long follow-up duration and performance of PCR genotyping should be implemented in programmatic surveillance of antimalarial drugs. © 2005 by the Infectious Diseases Society of America. All rights reserved.