We found a large body of evidence evaluating the efficacy and effectiveness of ORS, and a more limited number of studies assessing RHFs. Based on this evidence, we estimated that ORS may reduce diarrhoea mortality by up to 93%, but were unable to estimate the effectiveness of RHFs against diarrhoea mortality because no studies were conducted outside hospital setting, which is inconsistent with the definition of ‘home fluids’ ( and ). Whereas the overall quality of evidence supporting the effectiveness of ORS against diarrhoea mortality was low as a result of non-randomized study designs, our conclusions are strengthened by the consistency of the effect size and direction among the studies included and those excluded from the meta-analysis. Moreover, the biological basis for ORS, co-transport of glucose and sodium across the epithelial layer in the small intestine is well established and supports a protective effect of ORS against fluid losses and electrolyte imbalances.16
We correlated ORS effectiveness with coverage, using the absolute coverage levels reported for the intervention arms. However, in most community-based studies, ORS was also available and used at a low level in the comparison arms. The effective coverage level (difference in coverage between the intervention and comparison arms) was thus lower than the absolute coverage level used in our calculations. For this reason, our approach is conservative and likely overestimates the coverage needed to achieve a particular mortality reduction.
RHFs were not designed as an intervention to directly decrease diarrhoea mortality, but were instead intended to be used for home-based fluid management to prevent dehydration, with possible indirect effects on mortality. However, the only well-controlled studies of RHFs were conducted in hospital settings and included only sugar–salt solution and cereal–salt solution. Whereas we included these studies in our meta-analysis of RHF treatment failure, the results cannot be generalized to the administration of RHFs by a caregiver in the home and cannot be assumed to be representative of all current RHFs. Community-based studies of RHFs, which are not only inherently less controlled but also more relevant than hospital-based studies, have been conducted and were abstracted into Supplementary table 2
, but either did not include a relevant comparison arm or failed to adequately document the coverage achieved, making it difficult to interpret their results. Moreover, we were unable to find studies meeting our inclusion criteria that assessed other RHFs such as water and rice water. Thus, our findings may not be representative of the full range of RHFs.
ORS is a simple, proven intervention that can be used at the community and facility level to prevent and treat diarrhoeal dehydration and decrease diarrhoea mortality. Whereas ORS is highly effective, coverage levels remain low in most countries. It is essential that ORS coverage be increased to achieve reductions in diarrhoea mortality; to do so, operations and implementation research is needed to better understand how to deliver ORS effectively and promote its use at home and facility level as part of appropriate case management of diarrhoea.
In contrast to ORS, RHFs were designed and recommended as a home-based intervention to prevent diarrhoeal dehydration, but this message has become confused as diarrhoea control programmes have evolved. Moreover, for RHFs to be used appropriately at home, caregivers must be able to assess whether a child is dehydrated and correctly determine whether to provide RHFs or ORS. Thus, whereas there is evidence suggesting that RHFs may be effective in preventing dehydration, its correct implementation and the associated behaviour change communication messages are complex. From a programmatic perspective, promoting the use of ORS for all diarrhoea episodes might, therefore, be both simpler and more effective than promoting ORS and RHFs as a package and teaching caregivers when and how to use each.