The ethical and policy implications of research on income inequality and child well-being.

BACKGROUND AND OBJECTIVES: Child well-being is important for lifelong health and well-being. Although there is a robust evidence base linking social determinants of health (eg, relative poverty and income inequality) to child well-being, social and public health policy tends to focus on interventions to mitigate their effects, rather than remove the root causes. The goal of this study was to examine associations between child well-being and income inequality. METHODS: We compared reported rates of childhood well-being in the 2007 and 2013 UNICEF reports on child well-being in wealthy countries. Twenty indicators of child well-being (excluding child poverty) were defined consistently in both the 2007 and 2013 reports. These variables were used to create an indicator of change in child well-being over the approximate decade 2000 to 2010. For our analyses of income inequality, we used the Organization for Economic Cooperation and Development Gini coefficient of income inequality for 2009 and change between 2000 and 2009, respectively. RESULTS: The overall index of child well-being in 2013 was closely and negatively correlated with income inequality (r = -0.60, P = .004) but not with average income (r = -0.3460, P = .12). Adjustment for income inequality, children in relative poverty, and the child poverty gap did not change the lack of association between average income and child well-being in 2013 in wealthy countries. Between 2000 and 2010, child well-being scores improved most in Italy, Norway, Portugal, the United Kingdom, and Germany. The biggest declines were seen in Sweden, Canada, Japan, Switzerland, and France. Countries that experienced the largest increases in income inequality had significantly greater declines in child well-being (r = -0.51, P = .02). CONCLUSIONS: Children born into socioeconomically disadvantaged families suffer worse child well-being and its lifelong implications, in all societies, worldwide. Our analyses show, however, that some wealthy societies are able to mitigate these inequalities; these societies have better child well-being, on average. This outcome has less to do with specific welfare policies or targeted interventions for poor children than to a societal commitment to greater equality.

Income inequality and health: a causal review.

There is a very large literature examining income inequality in relation to health. Early reviews came to different interpretations of the evidence, though a large majority of studies reported that health tended to be worse in more unequal societies. More recent studies, not included in those reviews, provide substantial new evidence. Our purpose in this paper is to assess whether or not wider income differences play a causal role leading to worse health. We conducted a literature review within an epidemiological causal framework and inferred the likelihood of a causal relationship between income inequality and health (including violence) by considering the evidence as a whole. The body of evidence strongly suggests that income inequality affects population health and wellbeing. The major causal criteria of temporality, biological plausibility, consistency and lack of alternative explanations are well supported. Of the small minority of studies which find no association, most can be explained by income inequality being measured at an inappropriate scale, the inclusion of mediating variables as controls, the use of subjective rather than objective measures of health, or follow up periods which are too short. The evidence that large income differences have damaging health and social consequences is strong and in most countries inequality is increasing. Narrowing the gap will improve the health and wellbeing of populations.

Impact of ethnic density on adult mental disorders: narrative review.

BACKGROUND: The 'ethnic density hypothesis' is a proposition that members of ethnic minority groups may have better mental health when they live in areas with higher proportions of people of the same ethnicity. Investigations into this hypothesis have resulted in a complex and sometimes disparate literature. AIMS: To systematically identify relevant studies, summarise their findings and discuss potential explanations of the associations found between ethnic density and mental disorders. METHOD: A narrative review of studies published up to January 2011, identified through a systematic search strategy. Studies included have a defined ethnic minority sample; some measure of ethnic density defined at a geographical scale smaller than a nation or a US state; and a measure ascertaining mental health or disorder. RESULTS: A total of 34 papers from 29 data-sets were identified. Protective associations between ethnic density and diagnosis of mental disorders were most consistent in older US ecological studies of admission rates. Among more recent multilevel studies, there was some evidence of ethnic density being protective against depression and anxiety for African American people and Hispanic adults in the USA. However, Hispanic, Asian-American and Canadian 'visible minority' adolescents have higher levels of depression at higher ethnic densities. Studies in the UK showed mixed results, with evidence for protective associations most consistent for psychoses. CONCLUSIONS: The most consistent associations with ethnic density are found for psychoses. Ethnic density may also protect against other mental disorders, but presently, as most studies of ethnic density have limited statistical power, and given the heterogeneity of their study designs, our conclusions can only be tentative.

Inequality: an underacknowledged source of mental illness and distress.

Greater income inequality is associated with higher prevalence of mental illness and drug misuse in rich societies. There are threefold differences in the proportion of the population suffering from mental illness between more and less equal countries. This relationship is most likely mediated by the impact of inequality on the quality of social relationships and the scale of status differentiation in different societies.

Ethnic density effects on birth outcomes and maternal smoking during pregnancy in the US linked birth and infant death data set.

OBJECTIVES: We investigated whether mothers from ethnic minority groups have better pregnancy outcomes when they live in counties with higher densities of people from the same ethnic group-despite such areas tending to be more socioeconomically deprived. METHODS: In a population-based US study, we used multilevel logistic regression analysis to test whether same-ethnic density was associated with maternal smoking in pregnancy, low birthweight, preterm delivery, and infant mortality among 581 151 Black and 763 201 Hispanic mothers and their infants, with adjustment for maternal and area-level characteristics. RESULTS: Higher levels of same-ethnic density were associated with reduced odds of infant mortality among Hispanic mothers, and reduced odds of smoking during pregnancy for US-born Hispanic and Black mothers. For Black mothers, moderate levels of same-ethnic density were associated with increased risk of low birthweight and preterm delivery; high levels of same ethnic density had no additional effect. CONCLUSIONS: Our results suggest that for Hispanic mothers, in contrast to Black mothers, the advantages of shared culture, social networks, and social capital protect maternal and infant health.

Ethnic density effects on maternal and infant health in the Millennium Cohort Study.

Studies have suggested that members of ethnic minority groups might be healthier when they live in areas with a high concentration of people from their own ethnic group - in spite of higher levels of material deprivation typically found within such areas. We investigated the effects of area-level same-ethnic density on maternal and infant health, independent of area deprivation and individual socioeconomic status, in five ethnic minority groups. The study was a cross-sectional analysis within the UK Millennium Cohort Study and included mothers in five ethnic minority groups (Black African n=367, Bangladeshi n=369, Black Caribbean n=252, Indian n=462 and Pakistani n=868) and their 9-month-old infants. Outcome measures included: low birth weight, preterm delivery, maternal depression, self-rated health and limiting long-standing illness. Compared to those who live in areas with less than 5% of people from the same-ethnic minority population, Indian and Pakistani mothers were significantly less likely to report ever being depressed in areas with high same-ethnic density. There was a protective effect of ethnic density for limiting long-term illness among Bangladeshi mothers at 5-30% density and Pakistani mothers at all higher densities. Ethnic density was unrelated to infant outcomes and maternal self-rated health, and unrelated to any outcomes in Black African and Black Caribbean mothers and infants, possibly because no families in these groups lived at higher levels of same-ethnic density. Results were similar whether we examined smaller or larger residential areas. We conclude that, among ethnic minority mothers and infants in England, the relationship of ethnic density to health varies by ethnicity and outcome. For some measures of maternal health, in some ethnic groups, the psychosocial advantages of shared culture, social networks and social capital may override the adverse effects of material deprivation.

People like us: ethnic group density effects on health.

Studies examining the effects of neighbourhood characteristics have reported what has been called a 'group density' effect on health, such that members of low status minority communities living in an area with a higher proportion of their own racial or ethnic group tend to have better health than those who live in areas with a lower proportion. In this paper we survey published research on ethnic group density and health with the aim of stimulating further research. We situate the research question in the context of contemporary social epidemiology and provide a narrative review of studies of ethnic density and health. We go on to discuss processes which may underlie ethnic density effects, and highlight gaps in the literature and opportunities for further research. Although first recognised in studies of mental illness, 'group density' effects on physical health have been shown more recently. Generally, given individual material circumstances, living in a poorer area is associated with worse health. Members of ethnic minorities who live in areas where there are few like themselves are likely to be materially better off, and living in better neighbourhoods, than those who live in areas with a higher concentration. However, through the eyes of the majority community, they may be made more aware of belonging to a low status minority group, and the psychosocial effects of stigma may offset any advantage. If the psychological effects of stigma are sometimes powerful enough to override material advantage, this may have implications for our understanding of how low social status affects health more generally. As well as highlighting the importance of low social status, cultural isolation and social support to health and quality of life, this paper shows how an understanding of group density effects also has something to offer to our understanding of issues of prejudice, segregation, assimilation and integration in diverse societies.

Impact of social ties on self reported health in France: is everyone affected equally?

AIM: To examine the association of social ties and income with self reported health, in order to investigate if social ties have a greater impact on the health of people on low incomes compared to those financially better off. METHODS: A nationally representative cross-sectional study of 5205 French adults using data from questionnaires which asked about health, income and relationships with family and friends etc. RESULTS: Less than good self-rated health (SRH) is twice as frequently reported by people in the lowest income group than those in the highest income group. People with low incomes are also more likely to have felt alone on the previous day, received no phone call during the last week, have no friends, not be a member of a club, and to live alone. Socially isolated people report lower SRH. Likelihood ratio tests for interaction vs. main effect models were statistically significant for 2 of the measures of social ties, borderline for 2 others and non-significant for one. For 4 of the 5 indicators of social ties, larger odd ratios show that social isolation is more strongly associated with less than good SRH among people on low incomes compared to those with a higher income. CONCLUSION: Social isolation is associated with 'less than good' self-rated health. This effect appears to be more important for people on a low income.

Income inequality and socioeconomic gradients in mortality.

OBJECTIVES: We investigated whether the processes underlying the association between income inequality and population health are related to those responsible for the socioeconomic gradient in health and whether health disparities are smaller when income differences are narrower. METHODS: We used multilevel models in a regression analysis of 10 age- and cause-specific US county mortality rates on county median household incomes and on state income inequality. We assessed whether mortality rates more closely related to county income were also more closely related to state income inequality. We also compared mortality gradients in more- and less-equal states. RESULTS: Mortality rates more strongly associated with county income were more strongly associated with state income inequality: across all mortality rates, r= -0.81; P=.004. The effect of state income inequality on the socioeconomic gradient in health varied by cause of death, but greater equality usually benefited both wealthier and poorer counties. CONCLUSIONS: Although mortality rates with steep socioeconomic gradients were more sensitive to income distribution than were rates with flatter gradients, narrower income differences benefit people in both wealthy and poor areas and may, paradoxically, do little to reduce health disparities.

Child wellbeing and income inequality in rich societies: ecological cross sectional study.

OBJECTIVES: To examine associations between child wellbeing and material living standards (average income), the scale of differentiation in social status (income inequality), and social exclusion (children in relative poverty) in rich developed societies. DESIGN: Ecological, cross sectional studies. SETTING: Cross national comparisons of 23 rich countries; cross state comparisons within the United States. POPULATION: Children and young people. MAIN OUTCOME MEASURES: The Unicef index of child wellbeing and its components for rich countries; eight comparable measures for the US states and District of Columbia (teenage births, juvenile homicides, infant mortality, low birth weight, educational performance, dropping out of high school, overweight, mental health problems). RESULTS: The overall index of child wellbeing was negatively correlated with income inequality (r=-0.64, P=0.001) and percentage of children in relative poverty (r=-0.67, P=0.001) but not with average income (r=0.15, P=0.50). Many more indicators of child wellbeing were associated with income inequality or children in relative poverty, or both, than with average incomes. Among the US states and District of Columbia all indicators were significantly worse in more unequal states. Only teenage birth rates and the proportion of children dropping out of high school were lower in richer states. CONCLUSIONS: Improvements in child wellbeing in rich societies may depend more on reductions in inequality than on further economic growth.

The problems of relative deprivation: why some societies do better than others.

In this paper, we present evidence which suggests that key processes of social status differentiation, affecting health and numerous other social outcomes, take place at the societal level. Understanding them seems likely to involve analyses and comparisons of whole societies. Using income inequality as an indicator and determinant of the scale of socioeconomic stratification in a society, we show that many problems associated with relative deprivation are more prevalent in more unequal societies. We summarise previously published evidence suggesting that this may be true of morbidity and mortality, obesity, teenage birth rates, mental illness, homicide, low trust, low social capital, hostility, and racism. To these we add new analyses which suggest that this is also true of poor educational performance among school children, the proportion of the population imprisoned, drug overdose mortality and low social mobility. That ill health and a wide range of other social problems associated with social status within societies are also more common in more unequal societies, may imply that income inequality is central to the creation of the apparently deep-seated social problems associated with poverty, relative deprivation or low social status. We suggest that the degree of material inequality in a society may not only be central to the social forces involved in national patterns of social stratification, but also that many of the problems related to low social status may be amenable to changes in income distribution. If the prevalence of these problems varies so much from society to society according to differences in income distribution, it suggests that the familiar social gradients in health and other outcomes are unlikely to result from social mobility sorting people merely by prior characteristics. Instead, the picture suggests that their frequency in a population is affected by the scale of social stratification that differs substantially from one society to another.