Effect of a short course of iron polymaltose on acquisition of malarial parasitaemia in anaemic Indonesian schoolchildren: a randomized trial

Background Concern exists about the safety of iron supplementation given to individuals in malarious areas. The possible unfavourable impact of iron supplementation on malaria might be less when slow-release iron compounds are used instead of ferrous salts, because no toxic non-transferrin bound iron is formed. The aim of this study was to determine the effect of iron supplementation using the slow-release iron compound iron polymaltose (IPM) on the acquisition of malarial parasitaemia. Methods A randomized, placebo-controlled trial was performed in schoolchildren aged 5–18 years with mild or moderate anaemia on the Indonesian island Flores. Microscopic malaria-negative children were randomized to receive 8 weeks of IPM (6 mg elemental iron/kg/day) or placebo . The primary outcomes were the occurrence of microscopically detectable malarial parasitaemia at week 4, 8, 12 and 16 after start of treatment and the proportion of participants with real-time (RT) PCR positive malarial parasitaemia at week 16. Results 294 Children were assigned to the IPM group and 297 to the placebo group. Whereas IPM supplementation failed to increased haemoglobin or ferritin concentrations, the IPM group had a significantly higher rate of occurrence of microscopically detectable parasitaemia [hazard ratio 2.2, 95% C.I. 1.2–4.0; P = 0.01]. This higher rate was confined to iron-replete children. At the end of the study, 89% of the children in the IPM group had remained free from microscopically detectable parasitaemia vs 95% of children in the placebo group. The proportion of plasmodial RT-PCR positive children was similar in both groups at week 16 (IPM group 16.6% vs placebo group 14.3%; P = 0.47). When analysis was restricted to iron-replete children (serum ferritin ≥30 µg/l), there was a trend for a higher proportion being RT-PCR positive at week 16 in the IPM group compared with the placebo group (20 vs 13.3%; P = 0.07). Erythrocyte microcytosis was an independent risk factor for microscopically detectable malarial parasitaemia. Conclusions A short course of IPM should be used cautiously in anaemic children in malaria endemic areas, as it has limited efficacy in treating iron deficiency, while it increases the rate of microscopic malarial parasitaemia in those with replete iron stores. Trial registration ISRCTN 83091970. Registered 16 May 2012 (retrospectively registered) Electronic supplementary material The online version of this article (doi:10.1186/s12936-017-1691-5) contains supplementary material, which is available to authorized users.