Maternal and child health

In children under five in low- and middle-income countries, what is the comparative association of household water treatment interventions versus improved water source infrastructure with the prevalence of stunting?

The gap

While the retrieved literature confirms associations between water quality and child growth (e.g., Abstracts 2, 5, 8), no study directly compares the efficacy of household water treatment interventions against improved water source infrastructure for reducing stunting, leaving the specific comparative question unresolved.

Study design

Systematic review with random-effects meta-analysis, including pairwise pooling and network meta-analysis for indirect comparison

High-level approach

Binary stunting prevalence is pooled as risk ratios and continuous HAZ as mean differences, each via a DerSimonian–Laird random-effects model; where a connected evidence network exists, a random-effects network meta-analysis provides the indirect comparison of household water treatment versus improved water source. Heterogeneity is quantified with I² and τ², with subgroup analyses by study design, age, WASH co-interventions, and setting, plus meta-regression exploring follow-up duration and baseline stunting prevalence as moderators.

Methodology

Design justification

A systematic review with random-effects meta-analysis is the appropriate framework for synthesising associational evidence across diverse LMIC settings, intervention modalities, and study designs, as the random-effects model explicitly accommodates anticipated between-study heterogeneity [[3],[4],[5]]. Network meta-analysis extends this by enabling indirect comparison of household water treatment versus improved water source infrastructure even where head-to-head trials are absent, provided a connected evidence network links both intervention types through a common comparator ^[4]. Pre-specified subgroup and sensitivity analyses further strengthen the review's ability to explore sources of heterogeneity and assess robustness to study quality.

Population

Children under five years of age in low- and middle-income countries, as defined by World Bank income classification, residing in households or communities where water-related interventions (household treatment or improved source infrastructure) have been implemented or observed.

Setting

Global synthesis of studies conducted in LMIC settings; no primary data collection site.

Sampling

Purposive / purposeful sampling of primary studies meeting pre-specified eligibility criteria from indexed databases.

Sample-size approach

n/a — this is a systematic review; the sample is the universe of eligible studies identified through systematic search. No a priori statistical power calculation applies. A meta-analysis will be conducted if ≥2 studies report comparable effect estimates for the same comparison-outcome pair; otherwise, a narrative synthesis will be used per SWiM guidelines.

Variables

Primary outcome: stunting prevalence (height-for-age z-score < −2) or mean HAZ difference in children <5. Exposure/comparator categories: (a) household water treatment interventions (e.g., chlorination, filtration, solar disinfection, boiling) versus no treatment or control; (b) improved water source infrastructure (e.g., piped water, protected wells/springs, boreholes) versus unimproved sources; (c) household treatment versus improved source (indirect comparison via network meta-analysis or separate pooled estimates). Effect modifiers/covariates: child age, diarrhoea prevalence as intermediate outcome, sanitation co-interventions, handwashing co-interventions, nutritional supplementation, rural versus urban setting, study design (RCT vs. observational), follow-up duration, and baseline stunting prevalence.

Data sources

Systematic searches of PubMed/MEDLINE, Scopus, Cochrane CENTRAL, Web of Science, and grey literature (WHO, UNICEF, World Bank databases). Search strategy will combine terms for: (household water treatment OR water filtration OR chlorination OR solar disinfection OR boiling OR improved water source OR piped water OR protected well) AND (stunting OR height-for-age OR child growth OR linear growth OR HAZ) AND (child* OR under-five OR preschool) AND (low-income OR middle-income OR LMIC OR developing countr*). Citation tracking of included studies and prior reviews [[3,4,5]] will identify additional records. Two reviewers will independently screen titles/abstracts and full texts; disagreements resolved by a third reviewer. Data extraction will follow a piloted standardized form. Risk of bias assessment will use the Cochrane RoB 2 tool for RCTs [[2]] and the ROBINS-I tool for observational studies [[1]]. Certainty of evidence will be assessed using GRADE.

Time

6–9 months for protocol registration, systematic search, screening, data extraction, risk-of-bias assessment, meta-analysis, and manuscript preparation.

Cost

Low — primarily requires access to institutional library databases (PubMed, Scopus, Cochrane, Web of Science), reference management software, and statistical software (R, which is free). No primary data collection costs. Possible small cost for PROSPERO registration and publication fees.

Ethics

No IRB approval required — systematic review of published, de-identified aggregate data. Protocol will be registered on PROSPERO prior to screening to ensure transparency.

Grounding references

Determinants of stunting in Indonesian children: evidence from a cross-sectional survey indicate a prominent role for the water, sanitation and hygiene sector in stunting reduction — Torlesse H, Cronin AA, Sebayang SK, Nandy R · BMC Public Health, 2016 · DOI 10.1186/s12889-016-3339-8
Effects of water quality, sanitation, handwashing, and nutritional interventions on diarrhoea and child growth in rural Kenya: a cluster-randomised controlled trial — Null C, Stewart CP, Pickering AJ, Dentz HN, Arnold BF, Arnold CD · The Lancet Global Health, 2018 · DOI 10.1016/s2214-109x(18)30005-6
Safe Drinking Water and Its Impact on Children's Growth and Development: A Systematic Review. — Rosemiarti T, Sunardi D, Putri NM · International journal of environmental research and public health, 2026 · DOI 10.3390/ijerph23030313
Effectiveness of interventions to improve drinking water, sanitation, and handwashing with soap on risk of diarrhoeal disease in children in low-income and middle-income settings: a systematic review and meta-analysis — Jennyfer Wolf, Sydney Hubbard, Michael Bräuer, Argaw Ambelu, Benjamin F. Arnold, Robert Bain · The Lancet, 2022 · DOI 10.1016/s0140-6736(22)00937-0
Effect of Household Source of Drinking Water on Malnutrition among under Five Children in Ethiopia: Systematic Review and Meta-Analysis — Birhane M, Sisay G, Seid A · 2026 · DOI 10.21203/rs.3.rs-8659735/v1

Full protocol

Detailed design

Systematic review with random-effects (DerSimonian–Laird) meta-analysis [[3],[4],[5]]. The review will identify, appraise, and pool primary studies examining the association between household water treatment interventions and improved water source infrastructure and the prevalence of stunting among children under five in LMICs. Where ≥2 studies report comparable effect estimates for the same comparison-outcome pair,…

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