In a southern border province of Lao PDR, we compared the efficacy of antimalarial drug combinations in patients aged >or=1 year with uncomplicated Plasmodium falciparum malaria: monotherapy with either mefloquine (MQ), chloroquine (CQ), or sulphadoxine/pyrimethamine (SP) vs. the combination of both CQ and SP. Follow-up time was 14 days. Of 265 P. falciparum positive patients, 119 were enrolled in the drug trial. Significantly more patients treated with CQ than with SP developed early or late treatment failure [44.8%vs. 17.9%, relative risk (RR) = 2.51, 95% CI 1.03-6.12]. In the SP group, 82.1% were sensitive and 17.9% were treatment failures. The combination treatment CQ plus SP resulted in 83.3% sensitivity and 16.7% treatment failures. Combination treatment has no advantage over monotherapy with SP (RR = 1.01, 95% CI 0.8-1.3). All patients who received MQ for treatment (total dose 25 mg/kg) were cured within the 14 days of follow-up. The findings of this study suggest that use of CQ as first-line treatment of uncomplicated malaria in the Lao PDR has to be reconsidered. The combination of both CQ and SP has been discussed as a cost-effective alternative treatment, but in our patient population achieved no better results than single therapy with SP.
