Their indicators are under 5 weight for age, weight for height and height for age. After a systematic, thorough and transparent search process they identify 14 studies with good evaluation designs.
These are very good researchers, so what did they find?
These are the authors' conclusions:
"This review provides evidence that some water, sanitation and hygiene (WASH) interventions (specifically solar disinfection of water, provision of soap, and improvement of water quality) may slightly improve height growth in children under five years of age. The quality of the evidence is generally poor and the overall estimates presented are based only on meta-analyses of data from interventions of relatively short duration (9-12 months) from only a small selection of possible WASH interventions. These estimates are therefore not applicable to the effect that wider WASH interventions may have on child nutritional status."
A bit depressing, no? Some interventions, may slightly improve height growth in children under five. The authors conclude that the interventions have too short a duration, and there are not enough good evaluations.
Lets look a bit closer at the height for age results:
- 12 studies
- 8 countries (4 in South Asia, 3 in Sub Saharan Africa, 1 in Central America)
- 8 studies from urban/slum/peri urban settings, 4 from rural areas
- 8 studies find a positive effect (2 fairly large peri urban South Africa, rural Cambodia and rural Ethiopia), 1 finds no effect and 3 find a negative effect (and this is with a control group to take care of differences in differences)
First, don't give up on WASH Interventions--the theory of change is very strong and this is only a small set of intervention types and settings.
Second invest in good intervention designs--some of the interventions worked, now find out why.
Third, for goodness sake, stick with the interventions beyond 12 months--why would you expect profound behaviour change in less?
Finally, fund a good evaluation--poor evaluations save money in the short run but corrupt the decision making process and squander resources in the medium run.
Do these results wash? Unfortunately they do. The authors end on a hopeful note--there are currently studies underway on interventions that have a chance to work and where an impact, if present, has a chance to be detected.
Are you frustrated with such reviews? I am, but they can only survey what is out there. If they serve to stimulate the funding of better interventions and evaluations they will have served their purpose. Don't wash your hands of them--just be really careful how you use them.