摘要：It has been suggested that people in racial/ethnic minority groups are healthier when they live in areas with a higher concentration of people from their own ethnic group, a so-called ethnic density effect. Ethnic density effects are still contested, and the pathways by which ethnic density operates are poorly understood. The aim of this study was to systematically review the literature examining the ethnic density effect on physical health, mortality, and health behaviors. Most studies report a null association between ethnic density and health. Protective ethnic density effects are more common than adverse associations, particularly for health behaviors and among Hispanic people. Limitations of the literature include inadequate adjustment for area deprivation and limited statistical power across ethnic density measures and study samples. IT HAS BEEN SUGGESTED THAT people in racial/ethnic minority groups are healthier when they live in areas with a higher concentration of people from their own racial/ethnic group, a so-called ethnic density effect. 1,2 Ethnic density, defined as the proportion of ethnic minority residents in an area, is generally thought of in relation to the negative association between residential segregation and health. However, when the detrimental association between concentrated area deprivation and health is accounted for, and the focus is placed on the association between living among other ethnic minority people and health, ethnic density can also be considered in terms of social networks and supportive communities. Theoretical discourses of the ethnic density effect propose that positive health outcomes are attributed to the protective and buffering effects that enhanced social cohesion, mutual social support, and a stronger sense of community and belongingness provide from the direct or indirect consequences of discrimination and racial harassment, as well as from the detrimental effects of low-status stigma. 3–6 Studies to date on ethnic density and health have yielded inconsistent results, with some studies finding a protective ethnic density effect and others reporting a detrimental or null association. The discrepancy in results may arise because of numerous study differences. Variations in national and migration contexts have led to a wide range of racial/ethnic groups and densities being investigated, and studies have used a variety of area definitions to operationalize ethnic density, and have adjusted for different demographic and socioeconomic confounding factors. In addition to inconsistent findings, the possible mechanisms by which ethnic density affects health have not yet been fully explained, leaving the relationship between ethnic density and health poorly understood. A clear understanding of the literature on the ethnic density effect would contribute to current debates on the individual and community assets available in diverse communities. And given repeated, albeit not consistent, reports of ethnic density effects on health despite the increased levels of deprivation found in areas with high proportions of ethnic minority residents, 3,7,8 an appreciation of the ethnic density effect and the pathways by which it operates might also help in disentangling psychosocial influences on health from the effects of material factors, 5 making an important contribution to the field of social epidemiology. In a parallel piece of work we have undertaken a systematic review of the ethnic density literature on mental health. 9 Our purpose in this study was to systematically review the literature examining the ethnic density effect on physical health, mortality, and health behaviors. We employed a systematic search to eliminate potential biases caused by study selection, and we utilized the flexibility of a narrative synthesis to accommodate the diversity of studies.
