Estimating national, demographic, and socioeconomic disparities in water insecurity experiences in low-income and middle-income countries in 2020-21: a cross-sectional, observational study using nationally representative survey data.

BACKGROUND: We are facing a global water crisis. However, because most water indicators assess physical availability or infrastructure in aggregate, knowing which sociodemographic groups experience water insecurity is difficult. We aimed to assess the prevalence of water insecurity across low-income and middle-income countries (LMICs) and examine how it varies by sociodemographic characteristics and exposure to life disruptions due to the COVID-19 pandemic across and within countries. METHODS: In this observational study, we used Individual Water Insecurity Experiences (IWISE) scale data from a cross-sectional, nationally representative sample of individuals aged 15 years and older (defined as adults) in 31 LMICs. The IWISE scale range is 0-36, and water insecurity was defined as a score of 12 or higher. We used multivariable linear regression models to assess how individual-level experiences with water insecurity related to sociodemographic characteristics in each country, region, and the pooled sample. FINDINGS: 45 555 individuals from 31 LMICs completed the IWISE module between Sept 4, 2020, and Feb 24, 2021, and were included in the 2020 Gallup World Poll (GWP) database; 45 365 individuals had sufficient data to estimate the prevalence of water insecurity. 42 918 individuals from 30 LMICs had sufficient data to assess sociodemographic characteristics associated with water insecurity, and 39 161 individuals in 29 countries had sufficient data to assess how IWISE scale scores covaried with life disruptions due to the COVID-19 pandemic. The overall prevalence of water insecurity in 2020 was 14·2%, ranging by region from 36·1% in the sub-Saharan Africa region to 9·1% in the Asia region, and by country from 63·9% in Cameroon to 3·6% in China. In the pooled model including sociodemographic and COVID-19 factors, difficulty getting by on household income (vs no difficulty getting by: ß 2·76 [95% CI 2·45-3·07]), living in the outskirts of a city (vs living in a large city: 0·85 [0·29-1·41]), and being greatly affected by the COVID-19 pandemic (vs not being affected: 2·36 [1·96-2·77]) were strongly associated with higher IWISE scores. In country and regional models, the sociodemographic factors most consistently associated with higher IWISE scores were difficulty getting by on household income and life disruptions due to the COVID-19 pandemic, but the strength of these associations varied across countries and regions. INTERPRETATION: Through extrapolation of these nationally representative data, we estimate that hundreds of millions of people had life-altering experiences with water insecurity globally in 2020, and that their sociodemographic characteristics vary by country and region. Additional individual-level measurements globally could help pinpoint the characteristics of those who are most water insecure, thereby guiding the development of context-specific policy and interventions that will best serve those most affected. FUNDING: Carnegie Corporation, Northwestern University, and USAID.

The Individual Water Insecurity Experiences (IWISE) Scale: reliability, equivalence and validity of an individual-level measure of water security.

OBJECTIVE: The lack of a validated and cross-culturally equivalent scale for measuring individual-level water insecurity has prevented identification of those most vulnerable to it. Therefore, we developed the 12-item Individual Water InSecurity Experiences (IWISE) Scale to comparably measure individual experiences with access, use, and stability (reliability) of water. Here, we examine the reliability, cross-country equivalence, and cross-country and within-country validity of the scale in a cross-sectional sample. METHODS: IWISE items were implemented by the Gallup World Poll among nationally representative samples of 43 970 adults (>15 y) in 31 low-income and middle-income countries (LMICs). Internal consistency was assessed with Cronbach's alpha. Equivalence was tested using multigroup confirmatory factor analysis (MGCFA), the alignment method, and item response theory. Cross-country validity was assessed by regressing mean national IWISE scores on measures of economic, social, and water infrastructure development. Within-country validity was tested with logistic regression models of dissatisfaction with local water quality by IWISE score and regressing individual IWISE scores on per capita household income and difficulty getting by on current income. FINDINGS: Internal consistency was high; Cronbach's alpha was ≥0.89 in all countries. Goodness-of-fit statistics from MGCFA, the proportion of equivalent item thresholds and loadings in the alignment models, and Rasch output indicated equivalence across countries. Validity across countries was also established; country mean IWISE scores were negatively associated with gross domestic product and percentage of the population with access to basic water services, but positively associated with fertility rate. Validity within countries was also demonstrated; individuals' IWISE scores were positively associated with greater odds of dissatisfaction with water quality and negatively associated with lower financial standing. CONCLUSIONS: The IWISE Scale provides an equivalent measure of individual experiences with water access and use across LMICs. It will be useful for establishing and tracking changes in the prevalence of water insecurity and identifying groups who have been 'left behind'.