Slum upgrading strategies involving physical environment and infrastructure interventions and their effects on health and socio‐economic outcomes

Abstract

Globally, over one billion slum dwellers reside in informal housing and despite some progress towards improving their lives, slum improvements have failed to keep pace with the growing numbers of urban poor. In this review we examine what might be done about this through "slum upgrading", which refers to improvements in physical environment and infrastructure in slum settings with implications for socioeconomic development and health. Since upgrading requires massive resource investment by government and non-government agencies, it is essential that these resources are invested in the most effective and efficient ways. Our review is the first comprehensive review of slum upgrading programmes across low and middle income countries, collating and synthesizing interventions to provide a broad picture of their impacts for different settings, interventions and outcomes 1. It also considers and exposes key methodological issues in undertaking systematic reviews of these sorts of complex interventions. Right from its inception, the review incorporated the perspectives of end users in order to be relevant for future research and policy. We involved a multi-disciplinary advisory group in defining its scope, helping ensure that it would be relevant across end users and provide a coherent message, and we focused specifically on physical environment and infrastructure interventions (including single and multi-component interventions). The review also strikes the often difficult balance between quantitative evaluation literature and qualitative studies, incorporating slum dwellers' perspectives, insights into implementation processes, and aspects showing how, why and where interventions work. One of the substantial challenges of reviewing this evidence base was that the studies were dispersed across different disciplines and grey literature sources. We reviewed published, unpublished and grey literature, and incorporated studies in languages other than English. In the end, we covered 26 different databases and 18 websites of key organisations, searching these with numerous terms that are used for specific slums or interventions. While the total number of studies on slums is large, few of these are meaningful causal studies. We had conceptual and methodological concerns with many studies, and discuss these in the review. However, despite their limitations, there remains some evidence of possible benefits from the interventions we were able to study. We found reductions in communicable diseases, particularly incidence of diarrhoea. The findings for parasitic infections – both incidence and severity – were mixed and, for socioeconomic outcomes, the evidence was also mixed for measures of financial poverty, and the quality of this evidence is low. One of the important outcomes of our review is the identification of important gaps in the current evidence. Rigorous studies, with a low risk of bias and longer follow-ups are needed to allow firm conclusions to be drawn on the impact of slum upgrading strategies. We believe that our review should be considered carefully by donors, implementers and evaluators, in the hope of resolving remaining uncertainties, and tackling problems such as the lack of literature on non-communicable diseases, maternal and perinatal conditions, quality of life, employment, education, social capital and crime. We have already done some stakeholder mapping and analysis to identify the 'who' and 'what' for disseminating the review and we will be using a variety of social media tools to ensure that the message of the review reaches the appropriate audience.