Water Treatment and Child Mortality: A Meta-analysis and Cost-effectiveness Analysis

Randomized controlled trials (RCTs) of water treatment are typically powered to detect effects on caregiver-reported diarrhea but not child mortality, as detecting mortality effects requires prohibitively large sample sizes.

To increase statistical power, we conducted a systematic review and meta-analysis. We replicated search and selection criteria from previous meta-analyses of RCTs aimed at improving water quality to prevent diarrhea in low- or middle-income countries which included children under 5 years old. We identified 52 RCTs and then obtained child mortality data from each study for which these data were collected and available, contacting authors of the study where necessary; this resulted in 18 studies.

Frequentist and Bayesian methods were used to estimate the effect of water treatment on child mortality among included studies. We estimated a mean cross-study reduction in the odds of allcause under-5 mortality of 25-28% (frequentist odds ratio, OR, 0.75; 95% CI 0.60 to 0.92; Bayes OR 0.72; 95% CrI 0.51 to 0.94). The results were qualitatively similar under alternative modeling and data inclusion choices. Taking into account heterogeneity across studies, the expected reduction in a new study is 25%.

We used the results to examine the cost-effectiveness of three water treatment approaches, pointof- collection chlorine dispensers, inline chlorination, and a program providing free chlorine 1 solution through maternal and child health (MCH) services. After accounting for delivery costs, we estimate a cost per expected DALY averted due to water treatment between USD 27 and USD 65, depending on approach. This suggests that water treatment is one of the most cost-effective health programs available.