Turley, R, Saith, R., Bhan, N, Rehfuess, E, and Carter, B, 2013. Slum upgrading strategies and their effects on health and socio-economic outcomes: a systematic review, 3ie Systematic Review 13. London: International Initiative for Impact Evaluation (3ie).Link to Source
Headline Findings: a summary statementThe authors found limited but consistent evidence to suggest that slum- upgrading strategies reduce the incidence of diarrhoea and also reduce water-related expenses incurred by people who live in slums.
Evidence BaseThe authors included five studies in the main analysis: one randomised controlled trial and four controlled before-and-after studies. Three of these studies evaluated slum-upgrading strategies with more than one component, one evaluated road paving only, and the other evaluated water supply. The authors also included nine supporting studies: six controlled studies with only post-intervention data and three uncontrolled before-and-after studies. Eight of these studies evaluated slum-upgrading strategies with more than one component, and one evaluated cement flooring only. The studies were conducted in Asian countries (India, Philippines and Indonesia) and Latin American countries (Argentina, Mexico and Brazil), and one supporting study was conducted in Cape Town, South Africa.
Implications for policy and practiceThe studies measured different interventions and outcomes, making it difficult to compare results, and many of the study designs had a medium or high risk of bias, or used a study design that the authors argued cannot be used to determine causality. Despite these limitations, the authors found limited but consistent evidence to suggest that slum-upgrading strategies reduce the incidence of diarrhoea and also reduce water-related expenses incurred by people who live in slums. The authors reported mixed results for whether slum upgrading reduced parasitic infections, communicable diseases, financial poverty or unemployment outcomes. Five studies included some limited information on the perspectives of people who live in slums. Suggestions for policy based on these perspectives include choosing appropriate locations for facilities, acknowledging preferences for private facilities, ensuring that infrastructure is suitable for the intended purpose, and ensuring that systems are in place for cleaning, maintenance and repair.
Implications for further researchThe authors recommend developing and using a reliable and comparable outcome measure to determine the effect of slum upgrading. They also note that planning evaluation at the same time as the design and delivery of the intervention gives the best potential for rigorous studies with a low risk of bias in determining causal effects. The authors recommend the use of qualitative and process information in addition to quantitative effectiveness data, given the complexity of delivering slum-upgrading interventions. The authors were unable to identify studies for many relevant outcomes, including the effects of slum upgrading on non-communicable diseases, maternal and perinatal health, injuries, quality of life, employment, education, social capital and crime.
Slums are parts of cities where housing and living conditions are exceptionally poor and the population density is high. Poor living conditions are related to poor health outcomes and low quality of life. Slum-upgrading strategies aim to improve the physical environment; such strategies include improving and installing sanitation, electricity, waste collection and footpaths.
To explore the effects of slum-upgrading strategies that involve improving the physical environment and infrastructure on the health, quality of life and socio-economic well-being of people living in urban slums in low- and middle-income countries.
The authors included randomised controlled trials, controlled before-and-after studies, and interrupted-time series assessing the effect of slum-upgrading strategies on the health, quality of life and socio-economic well-being of urban slum dwellers in low- and middle-income countries. They also included controlled studies with only post-intervention data and uncontrolled before-and-after studies to examine whether results were consistent and to provide supplementary evidence for the main analysis. The authors defined slum-upgrading strategies as strategies to improve the physical environment or infrastructure of slums, and they included strategies that also involved co-interventions such as providing funding or services. The authors searched academic and grey literature, both published and unpublished, with no restriction on language or publication dates. The search covered 28 databases, the websites of major international development organisations, reference lists of included studies and relevant journal titles. The authors also contacted experts and organisations. Two authors assessed the quality of each study, using GATE (graphical appraisal tool for epidemiological studies) and compiled risk-of-bias tables. Meta-analysis was not possible because the outcomes and interventions were too diverse, so the authors completed a narrative synthesis.
The authors have incorporated all the elements of a systematic review, including a comprehensive search strategy, and validated and standardised methods for double independent screening and data extraction, quality appraisal and critical synthesis. They have evaluated the body of evidence for each outcome, using the internationally recognised GRADE criteria.