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Methodological clarifications needed

Posted by plosmedicine on 31 Mar 2009 at 00:04 GMT

Author: Moussa Sarr
Position: Senior Epidemiologist
Institution: Westat
Submitted Date: January 30, 2007
Published Date: January 31, 2007
This comment was originally posted as a “Reader Response” on the publication date indicated above. All Reader Responses are now available as comments.

In their recently published paper, Becquet et al. (1) found that the 2-years rates of adverse health outcomes were similar among short-term breast-fed and formula-fed children. Mortality rates also did not differ significantly between these two groups and, after adjustment for pediatric HIV status, were similar to those observed among long-term breast-fed children. These results confirm the findings of two previuos trials in Kenya (2) and in Bostwana (3) highlighting the fact that with adequate support alternatives to prolonged breastfedding can be safe options for mothers to prevent mother-to-child transmission of HIV in African settings. HIV infected mothers who opt for alternatives to breastfeeding to protect their children from the HIV infection should be provided the necessary support to make their choice feasible.

There are, however, some methodological clarifications that are needed to be made regarding the incidence of Incidence rates of diarrhea, acute respiratory infection, and malnutrition. It was not clear if all repeated episodes of diarrhea and acute respiratory infection were taking into account to compute the incidence rates. A number of epidemiologists have been also advocating the use longitudinal prevalence instead of incidence for the longitudinal measure of morbidity associated with childhood diarrhea. (4) The longitudinal prevalence is defined by the number of episodes experienced by each child over a defined period (a measure of incidence) and the number of days of diarrhea divided by the total number of days of observation for each child (a measure denoted "longitudinal prevalence"). Longitudinal prevalence was found to be a better predictor of long-term health outcome in relationship to childhood diarrhea. (4)

1. Becquet R, Bequet L, Ekouevi DK, Viho I, Sakarovitch C, et al. Two-Year Morbidity–Mortality and Alternatives to Prolonged Breast-Feeding among Children Born to HIV-Infected Mothers in Côte d'Ivoire. PLoS Medicine Vol. 4, No. 1, e17 doi:10.1371.

2. Mbori-Ngacha D, Nduati R, John G, Reilly M, Richardson B, Mwatha A, Ndinya-Achola J, Bwayo J, Kreiss J. Morbidity and mortality in breastfed and formula-fed infants of HIV-1-infected women: A randomized clinical trial. JAMA 2001 Nov 21; 286(19):2413-20.

3. Thior I, Lockman S, Smeaton LM, Shapiro RL, Wester C, Heymann SJ, Gilbert PB, Stevens L, Peter T, Kim S, van Widenfelt E, Moffat C, Ndase P, Arimi P, Kebaabetswe P, Mazonde P, Makhema J, McIntosh K, Novitsky V, Lee TH, Marlink R, Lagakos S, Essex M; Mashi Study Team. Breastfeeding plus infant zidovudine prophylaxis for 6 months vs. formula feeding plus infant zidovudine for 1 month to reduce mother-to-child HIV transmission in Botswana: a randomized trial: the Mashi Study. JAMA. 2006 Aug 16;296(7):794-805.

4. Morris SS, Cousens SN, Kirkwood BR et al. Is prevalence of diarrhea a better predictor of subsequent mortality and weight gain than diarrhea incidence? Am J Epidemiol 1996; 144:582-88.

No competing interests declared.