Summary

BELOW is an article. write one page of summary forit breastfeeding for 6 months versus 3-4 months with mixed breastfeeding thereafter, resulted in the recommendation to promote exclusive breastfeeding for the first 6 months of life [9]. More recently, the authors of the Lancet nutrition series published a random effects meta-analysis estimating the increased risk of diarrheaspecific morbidity and mortality among children younger than 2 years in relation to suboptimal breastfeeding practices [7]. While these estimates provide confirmation of the protective effect of breastfeeding, they were based on a limited data set, rather than a complete systematic review, and thus a more thorough and updated revision is warranted. Building upon previous reviews, this systematic review and meta-analyses use carefully developed and standardized methods to focus on the effects of breastfeeding practices as they relate to diarrhea incidence, prevalence, mortality and hospitalization among children 0-23 months of age. Here we present a comprehensive systematic review and meta-analysis as evidence to be utilized by the Lives Saved Tool (LiST) to model the effect of breastfeeding practices on diarrhea-specific morbidity and mortality [10,11]. The results of our analysis will serve as the basis for generating projections of child lives that could be saved by increasing exclusive breastfeeding until 6 months of age and continued breastfeeding until 23 months of age. Methods We systematically reviewed all literature published from 1980 to 2009 to identify studies with data assessing levels of suboptimal breastfeeding as a risk factor for diarrhea morbidity and mortality outcomes. We conducted our initial search on July 28, 2009 and two updated searches on April 8 and May 5, 2010. All searches were completed in Pubmed, EMBASE, the Global Health Library Global Index and Regional Index, and the Cochrane central register for controlled trials using combinations of key search terms: breastfeeding, breast milk, human milk, diarrhea, gastroenteritis, morbidity, mortality, infant and child. To ensure the identification of all relevant literature, we also reviewed the references of included papers. After initially screening for eligibility based on title and abstract, we thoroughly reviewed full publications for inclusion and exclusion criteria outlined a priori. We included randomized controlled trials (RCT), cohort and observational studies that assessed suboptimal breastfeeding as a risk factor for at least one of the following outcomes: diarrhea incidence, diarrhea prevalence, diarrhea mortality, all-cause mortality, and diarrhea hospitalizations. Included studies were published in any language from 1980 - 2009 and were conducted in developing countries with a target population of children 0-23 months of age. We excluded studies reporting diarrhea as a result of only one microbial cause, and those with unclear methodology or data in a form that could not be extracted for meta-analysis. We also excluded studies reporting exclusive breastfeeding for children beyond 6 months of age and those failing to restrict the allocation of diarrhea outcomes to concurrent breastfeeding status. Additionally, we excluded morbidity studies with diarrhea recall beyond two weeks and mortality studies where the removal of deaths occurring within the first three to seven days of life was not possible. For studies reporting outcomes stratified by HIV status, we only abstracted data on HIV-negative infants and children. We abstracted data for each diarrhea outcome by breastfeeding exposure levels, which were classified according to current WHO definitions (Table 1) [12,13]. To allow for the comparability of breastfeeding labels and definitions derived from studies published over multiple decades, during which time breastfeeding definitions and terms evolved, we assigned the exposure categories described by each study to a WHO category on the basis of the study’s definition of that exposure category, not the authors’ category label. The majority of discrepancies between breastfeeding label and definition arose over the term ‘exclusive breastfeeding’. By current standards, ‘exclusive breastfeeding’ does not include the ingestion of anything other than breastmilk and prescribed vitamins and medications, and infants receiving non-nutritive liquids, such as waters and teas, are classified as ‘predominantly breastfed’ [12]. This distinction was not formally recommended until 1988 when a meeting of the Interagency Group for Action on Breastfeeding first proposed the development of a set of standardized breastfeeding definitions [14]. WHO officially integrated indicators differentiating between exclusive and predominant breastfeeding in 1991 [12]. As such, for this review we assumed the ‘exclusive breastfeeding’ category was more appropriately labelled ‘predominant breastfeeding’ for studies published prior to 1991, unless the study specifically defined exclusive breastfeeding according to the current definition. For studies that grouped exclusively and predominantly breastfed infants into a ‘fully breastfeeding’ category, we employed a conservative approach in which fully breastfeeding exposure was treated as predominant. We excluded studies that combined exposures other than exclusive and predominant breastfeeding into one breastfeeding category. In this review we did not seek to address the issue of early initiation of breastfeeding and prelacteal feeds. Thus, in assigning breastfeeding exposure, we did not differentiate between exclusive and predominant breastfeeding on the basis of receipt of prelacteal feeds during the first 3 days of life. Lamberti et al. BMC Public Health 2011, 11(Suppl 3):S15 http://www.biomedcentral.com/1471-2458/11/S3/S15 Page 2 of 12