Low and middle income countries (LMIC) are home to over 90% of the one billion people living in slums. Urban slums describe parts of cities where living conditions are exceptionally poor. The slums lack basic services and often have many people crowded into small living spaces. Slums can provide shelter and proximity to jobs, and communities are often social and supportive. However, poor living conditions and health are closely related, and illnesses such as diarrhoea, malaria, cholera and respiratory diseases are common.
Slum upgrading basically involves improving the physical environment, for example the water supply, sanitation, waste collection, electricity, drainage, road paving and street lighting. Additional strategies may be included to improve access to health, education and social services, increase residents’ income and secure legal rights to the land.
We found five main studies with suitable methods for examining the effect of slum upgrading on health, quality of life and social wellbeing (for example poverty). Nine supporting studies were also included, which used methods that could indicate associations between interventions and outcomes but could not assess whether interventions caused the effect. Only one main study had a low risk of bias, with the rest having a mixed or high risk of bias. The majority of supporting studies had a high risk of bias, meaning their methods had several limitations that made the study results unreliable. In addition, the studies measured different interventions and outcomes, making it difficult to compare results.
Overall, there was limited but consistent evidence to suggest that slum upgrading may reduce diarrhoea in slum dwellers and their water-related expenses. There were mixed results for whether slum upgrading reduced parasitic infections, general measures of communicable diseases, financial poverty and unemployment outcomes. There was very little information on other health or social outcomes, or which types of interventions were most beneficial. Some of the studies asked slum dwellers for their views and their experiences of slum upgrading interventions. They suggested a number of reasons why facilities were not used as intended and which may have reduced the benefits.
Future research, with improved study designs and common outcome measures, is needed to determine how best to improve the conditions of existing slums and to offer the most benefit to the health, quality of life and social wellbeing of slum dwellers.