Context and health: a systematic review of natural experiments among migrant populations

Abstract

Background: Studies on contextual effects on health often suffer from compositional bias and selective migration into contexts. Natural experiments among migrants may allow for the causal effect of contexts in generating health inequalities to be examined. We synthesised the evidence on and health from natural experiments among migrant populations. Methods: Systematic literature review searching the databases PubMed/MEDLINE, The Cochrane Library, Web of Science, CINAHL and Google Scholar for literature published until October 2022. 5870 studies were screened independently in duplicate using pre-defined criteria for inclusion: quantitative natural experiment methodology, migrant study population, context factor as treatment variable and health or healthcare outcome variable. Synthesis without meta-analysis was performed following data extraction and quality appraisal. Findings: The 46 included natural experiment studies provide causal evidence for the negative effects of neighbourhood disadvantage on physical health and mortality, while finding mixed effects on mental health. Studies comparing migrants with those that stayed behind demonstrate the detrimental effects of migration and adverse post-migratory contexts on physical health and mortality, while demonstrating favourable effects for mental health and child health. Natural experiments of policy contexts indicate the negative impacts of restrictive migration and social policies on healthcare utilization, mental health and mortality as well as the positive health effects when restrictions are lifted. Interpretation: Natural experiments can serve as powerful tools in reducing bias through self-selection. With careful consideration of causal pathways, results from migration contexts can serve as a magnifying glass for the effects of context for other population groups. Studies demonstrate the negative impacts for health which lie at the nexus of context and health. At the same time, they uncover the potential of health and welfare programs to counteract the disadvantages created by othering processes and promote healthy (post-migratory) contexts.

Local political climate and spill-over effects on refugee and migrant health: a conceptual framework and call to advance the evidence

“…However, for causal inference to be free of compositional bias, studies need to rule out self-selection of individuals and population groups into contexts. The use of natural experiment designs, if available, or analytical strategies such as instrumental variables, propensity score matching and/or difference-in-difference analysis will be required to ensure that contextual effects of local political climates are studied while minimising compositional bias through selective migration 76…”

“…The use of natural experiment designs, if available, or analytical strategies such as instrumental variables, propensity score matching and/or difference-in-difference analysis will be required to ensure that contextual effects of local political climates are studied while minimising compositional bias through selective migration. 76 A deeper knowledge of the relationships of political climate and population health may help to design interventions-at societal, community, health system or individual level-to counter exclusionary policies, prevent racist violence or mitigate its negative BMJ Global Health effects. We call for collective efforts among public health scientists in Europe to build coalitions between social sciences, conflict and violence studies, political science, data science, social psychologists and epidemiology to advance the theory, measurement, and analysis of such relationships.…”