Are studies underestimating the effects of sanitation on child nutrition?
Authors: Derek Headey
Journal: The Lancet Global Health (2016)

As other researchers have done, Amy Pickering and colleagues (November, 2015)1Pickering AJ Djebbari H Lopez C Coulibaly M Alzua ML Effect of a community-led sanitation intervention on child diarrhoea and child growth in rural Mali: a cluster-randomised controlled trial.Lancet Glob Health. 2015; 3: e701-e711Summary Full Text Full Text PDF Scopus (225) Google Scholar focused on short-recall diarrhoea incidence as the main outcome in their randomised trial of the effects of a community-led sanitation intervention in Mali. As Pickering and colleagues1Pickering AJ Djebbari H Lopez C Coulibaly M Alzua ML Effect of a community-led sanitation intervention on child diarrhoea and child growth in rural Mali: a cluster-randomised controlled trial.Lancet Glob Health. 2015; 3: e701-e711Summary Full Text Full Text PDF Scopus (225) Google Scholar noted, this indicator has well known flaws associated not only with seasonality, but also with potential reporting bias and other measurement errors. These flaws raise the possibility of crucial type II errors that justify a serious reappraisal of the long-standing practice of using this indicator as the primary means to evaluate sanitation interventions. With good reasons, then, Pickering and colleagues chose child anthropometric indicators, particularly growth outcomes, as secondary outcomes. Before this study,1Pickering AJ Djebbari H Lopez C Coulibaly M Alzua ML Effect of a community-led sanitation intervention on child diarrhoea and child growth in rural Mali: a cluster-randomised controlled trial.Lancet Glob Health. 2015; 3: e701-e711Summary Full Text Full Text PDF Scopus (225) Google Scholar however, the existing experimental literature neglected the important issue of the timing of growth faltering, which almost entirely takes place in utero and in the first 24 months of life.2Victora CG de Onis M Curi Hallal P Blössner M Shrimpton R Worldwide timing of growth faltering: revisiting implications for interventions.Pediatrics. 2009; 2010: 473-480Google Scholar Since exposure to improved sanitation was quite short in all of these evaluations (lasting 6–24 months) and all these studies focused on children aged 0–59 months, the relevant statistical tests mixed together younger children for whom sanitation plausibly benefits linear growth with older children for whom sanitation plausibly offers little or no benefits. Consistent with this so-called exposure bias, Pickering and colleagues1Pickering AJ Djebbari H Lopez C Coulibaly M Alzua ML Effect of a community-led sanitation intervention on child diarrhoea and child growth in rural Mali: a cluster-randomised controlled trial.Lancet Glob Health. 2015; 3: e701-e711Summary Full Text Full Text PDF Scopus (225) Google Scholar reported no effect of sanitation interventions on linear growth for the children aged from 24 months to less than 60 months (2–5 years) at enrolment, but showed an effect for those aged younger than 24 months (<2 years) at enrolment, and the largest effect for children aged younger than 12 months (<1 year) at enrolment. Moreover, since findings published in 2015 from the SHINE project3Prendergast AJ Rukobo S Chasekwa B et al.Stunting is characterized by chronic inflammation in Zimbabwean infants.PLoS One. 2014; 9: e86928Crossref PubMed Scopus (160) Google Scholar showed that environmental enteropathy (also termed environmental enteric dysfunction1Pickering AJ Djebbari H Lopez C Coulibaly M Alzua ML Effect of a community-led sanitation intervention on child diarrhoea and child growth in rural Mali: a cluster-randomised controlled trial.Lancet Glob Health. 2015; 3: e701-e711Summary Full Text Full Text PDF Scopus (225) Google Scholar) starts in utero through maternal infection,3Prendergast AJ Rukobo S Chasekwa B et al.Stunting is characterized by chronic inflammation in Zimbabwean infants.PLoS One. 2014; 9: e86928Crossref PubMed Scopus (160) Google Scholar full exposure to improved sanitation facilities ought to, theoretically, include children whose mothers had sanitation for the full duration of their pregnancy, if not before. Collectively these findings suggest that future sanitation intervention trials should consider focusing on child growth as the primary indicator of interest; record when toilet facilities were first put in to use (to measure duration of exposure); and focus on assessing the nutritional effects on younger children (0–2 years), including exposure in utero. I declare no competing interests. Are studies underestimating the effects of sanitation on child nutrition? – Authors' replyShould child growth replace diarrhoea as the primary child health outcome for sanitation trials? We appreciate Derek Headey's comment in relation to our trial1 that the window of opportunity to plausibly affect growth faltering is from in utero up to 24 months, and therefore that sanitation trials should focus growth assessments in children with exposure to the intervention who are younger than 24 months. Ongoing sanitation trials in rural Kenya ( NCT01704105 ), Bangladesh ( NCT01590095 ), and Zimbabwe ( NCT01824940 ) have chosen to enrol target children in utero precisely because of the recognition that child stunting and environmental enteric dysfunction can begin before birth. Full-Text PDF Open Access