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Meta-Analysis
. 2022 Jul 2;400(10345):48-59.
doi: 10.1016/S0140-6736(22)00937-0.

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  1 , Sydney Hubbard  2 , Michael Brauer  3 , Argaw Ambelu  4 , Benjamin F Arnold  5 , Robert Bain  6 , Valerie Bauza  2 , Joe Brown  7 , Bethany A Caruso  8 , Thomas Clasen  2 , John M Colford Jr  5 , Matthew C Freeman  2 , Bruce Gordon  9 , Richard B Johnston  9 , Andrew Mertens  5 , Annette Prüss-Ustün  9 , Ian Ross  10 , Jeffrey Stanaway  11 , Jeff T Zhao  11 , Oliver Cumming  10 , Sophie Boisson  9
Affiliations
Meta-Analysis

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 et al. Lancet. .

Erratum in

  • Department of Error.
    [No authors listed] [No authors listed] Lancet. 2022 Jul 23;400(10348):272. doi: 10.1016/S0140-6736(22)01341-1. Lancet. 2022. PMID: 35871811 Free PMC article. No abstract available.
  • Department of Error.
    [No authors listed] [No authors listed] Lancet. 2023 Jun 17;401(10393):2040. doi: 10.1016/S0140-6736(23)01199-6. Lancet. 2023. PMID: 37330745 Free PMC article. No abstract available.

Abstract

Background: Estimates of the effectiveness of water, sanitation, and hygiene (WASH) interventions that provide high levels of service on childhood diarrhoea are scarce. We aimed to provide up-to-date estimates on the burden of disease attributable to WASH and on the effects of different types of WASH interventions on childhood diarrhoea in low-income and middle-income countries (LMICs).

Methods: In this systematic review and meta-analysis, we updated previous reviews following their search strategy by searching MEDLINE, Embase, Scopus, Cochrane Library, and BIOSIS Citation Index for studies of basic WASH interventions and of WASH interventions providing a high level of service, published between Jan 1, 2016, and May 25, 2021. We included randomised and non-randomised controlled trials conducted at household or community level that matched exposure categories of the so-called service ladder approach of the Sustainable Development Goal (SDG) for WASH. Two reviewers independently extracted study-level data and assessed risk of bias using a modified Newcastle-Ottawa Scale and certainty of evidence using a modified Grading of Recommendations, Assessment, Development, and Evaluation approach. We analysed extracted relative risks (RRs) and 95% CIs using random-effects meta-analyses and meta-regression models. This study is registered with PROSPERO, CRD42016043164.

Findings: 19 837 records were identified from the search, of which 124 studies were included, providing 83 water (62 616 children), 20 sanitation (40 799 children), and 41 hygiene (98 416 children) comparisons. Compared with untreated water from an unimproved source, risk of diarrhoea was reduced by up to 50% with water treated at point of use (POU): filtration (n=23 studies; RR 0·50 [95% CI 0·41-0·60]), solar treatment (n=13; 0·63 [0·50-0·80]), and chlorination (n=25; 0·66 [0·56-0·77]). Compared with an unimproved source, provision of an improved drinking water supply on premises with higher water quality reduced diarrhoea risk by 52% (n=2; 0·48 [0·26-0·87]). Overall, sanitation interventions reduced diarrhoea risk by 24% (0·76 [0·61-0·94]). Compared with unimproved sanitation, providing sewer connection reduced diarrhoea risk by 47% (n=5; 0·53 [0·30-0·93]). Promotion of handwashing with soap reduced diarrhoea risk by 30% (0·70 [0·64-0·76]).

Interpretation: WASH interventions reduced risk of diarrhoea in children in LMICs. Interventions supplying either water filtered at POU, higher water quality from an improved source on premises, or basic sanitation services with sewer connection were associated with increased reductions. Our results support higher service levels called for under SDG 6. Notably, no studies evaluated interventions that delivered access to safely managed WASH services, the level of service to which universal coverage by 2030 is committed under the SDG.

Funding: WHO, Foreign, Commonwealth & Development Office, and National Institute of Environmental Health Sciences.

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Conflict of interest statement

Declaration of interests JW and BG report grants from the UK Foreign, Commonwealth and Development Office, during the conduct of the study. SH reports grants from the National Institute of Environmental Health Sciences, during the conduct of the study. MB reports grants from Bill & Melinda Gates Foundation during the conduct of the study. BFA reports grants from National Institutes of Health, and grants and non-financial support from Bill & Melinda Gates Foundation, outside the submitted work. MCF reports personal fees from Reckitt, outside the submitted work. AM has received funding as a statistical consultant on The Lancet Commission on water, sanitation and hygiene, and health to analyse the associations between water, sanitation, hygiene, and handwashing and child health using Multiple Indicator Cluster Survey data and to complete an individual-participant data meta-analysis of WASH trials on pathogen contamination in the environment and child health. All other authors declare no competing interests.

Figures

Figure 1
Figure 1
Exposure scenario for drinking water services POU=point-of-use.
Figure 2
Figure 2
Exposure scenario for sanitation (A) and hygiene (B) services
Figure 3
Figure 3
Study selection *Including 78 separate studies for water comparisons, 19 separate studies for sanitation comparisons, and 41 separate studies for hygiene comparisons, as well as 12 studies that provided data on more than one analysis, two of which provided data on all three analyses.
Figure 4
Figure 4
Effects of hygiene interventions on risk of diarrhoea Weights are from the random-effects model. RR=relative risk.
See this image and copyright information in PMC

Comment in

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