IJE Advance Access originally published online on December 14, 2006
International Journal of Epidemiology 2007 36(1):243-244; doi:10.1093/ije/dyl260
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Letters to the Editor |
Improving malaria mortality estimates for rural Africa by adding further studies: Authors reply to Ndugwa et al.
1 Division of Parasitic Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, United States.
2 Program for Appropriate Technology for Health (PATH), Ferney-Voltaire, France.
* Corresponding author. Centers for Disease Control and Prevention, Mailstop F22, 4770 Buford Highway, Atlanta, GA 30341-3724. E-mail: axr9{at}cdc.gov
We thank Ndugwa et al. for their comments1 on our recent estimates of malaria mortality among African children in the year 2000.2 Ndugwa et al. recognize the reasonableness of our inclusion criteria, but claim that many relevant studies were omitted. They also present data from Nouna, Burkina Faso, that could improve future estimates.
Regarding the comment that we excluded many relevant studies (presumably because of strict inclusion criteria), we remind Ndugwa et al. that a sensitivity analysis (Model B in Table 4 of reference 2) that included 11 additional studies that met nearly all the inclusion criteria produced results that were very similar to our best estimates. Furthermore, aside from their own study, Ndugwa et al. do not say what these other many relevant studies are. We invite them, and others, to share such studies (and to make them publicly available) to improve the representativeness and precision of future estimates.
We appreciate the results from Nouna and the effort that Ndugwa et al. made to have their data match our inclusion criteria and methods, enabling rate comparisons and inclusion of this data point in future updates. We suspect that the addition of the Nouna data would not change the overall estimate substantially. At a rate of 15.2 deaths/1000 person-years, the Nouna data point is within the range of the 15 rates (1.9–24.0/1000 person-years) included in our best model for rural settings with high-intensity malaria transmission. Its sample size relative to the original 15 data points would probably not give this additional study excessive influence.
Notably, the high coverage of insecticide-treated nets in part of the Nouna research site3 illustrates an important challenge for future estimates of malaria burden. For the 2000 estimates, it was reasonable to assume that coverage of malaria interventions was generally very low (except perhaps case management) and its impact on mortality burden could be ignored. In contrast, estimates for the next milestone (e.g. 2010) will need to account for increasing intervention coverage in many countries.
Ultimately, the justification today for additional and sustained resources to combat malaria is not built around exact estimates of malaria's burden in past years, but on the availability of effective and affordable interventions to control and prevent malaria. Future assessments of malaria burden will need to track the evidence that scale-up is happening (i.e. population coverage data for each of the interventions) and link that evidence to the continued measurement of infection, disease and death. Roll Back Malaria's Monitoring and Evaluation Reference Group (http://www.rbm.who.int/merg.html) is developing recommendations for such evaluation methods.
References
1 Ndugwa RP, Müller O, Kouyaté B, Becher H, Ramroth H. Improving malaria mortality estimates for rural Africa by adding further studies. Int J Epidemiol. doi:10.1093/ije/dyl259.
2 Rowe AK, Rowe SY, Snow RW, et al. The burden of malaria mortality among African children in the year 2000. Int J Epidemiol (2006) 35:691–704.
3 Müller O, Traore C, Kouyate B, et al. Effects of insecticide-treated bednets during early infancy in an African area of intense malaria transmission: a randomized controlled trial. Bull World Health Organ (2006) 84:120–26.[CrossRef][ISI][Medline]
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