Income inequality and self-rated health in US metropolitan areas: A multi-level analysis

Income inequality has been found to affect health in a number of international and cross-national studies. Using data from a telephone survey of adults in the United States, this study analyzed the effect of metropolitan level income inequality on self-rated health. It combined individual data from the 2000 Behavioral Risk Factor Surveillance System with metropolitan level income data from the 2000 Census. After controlling for smoking, age, education, Black race, Hispanic ethnicity, sex, household income, and metropolitan area per capita income, this study found that for each 1 point rise in the GINI index (on a hundred point scale) the risk of reporting Fair or Poor self-rated health increased by 4.0% (95% confidence interval 1.6–6.5%). Given that self-rated health is a good predictor of morbidity and mortality, this suggests that metropolitan area income inequality is affecting the health of US adults.     

Social capital, income inequality, and self-rated health in 45 countries

There has been growing interest in the relationship between the social environment and health. Among the concepts that have emerged over the past decade to examine this relationship are socio-economic inequality and social capital. Using data from the World Values Survey and the World Bank, we tested the hypothesis that self-rated health is affected by social capital and income inequality cross-nationally. The merit of our approach was that we used multilevel methods in a larger and more diverse sample of countries than used previously. Our results indicated that, for a large number of diverse countries, commonly used measures of social capital and income inequality had strong compositional effects on self-rated health, but inconsistent contextual effects, depending on the countries included. Cross-level interactions suggested that contextual measures can moderate the effect of compositional measures on self-rated health. Sensitivity tests indicated that effects varied in different subsets of countries. Future research should examine country-specific characteristics, such as differences in cultural values or norms, which may influence the relationships between social capital, income inequality, and health.     

Social capital and self-rated health--a study of temporal (causal) relationships

Despite the vast amount of research over the past fifteen years, there is still lively debate surrounding the role of social capital on individual health outcomes. This seems to stem from a lack of consistency regarding the definition, measurement and plausible theories linking this contextual phenomenon to health. We have further identified a knowledge gap within this field - a distinct lack of research investigating temporal relationships between social capital and health outcomes. To remedy this shortfall, we use four waves of the British Household Panel Survey to follow the same individuals (N = 8114) between years 2000 and 2007. We investigate temporal relationships and association between our outcome variable self-rated health (SRH) and time-lagged explanatory variables, including three individual-level social capital proxies and other well-known health determinants. Our results suggest that levels of the social capital proxy 'generalised trust' at time point (t - 1) are positively associated with SRH at subsequent time point (t), even after taking into consideration levels of other well-known health determinants (such as smoking status) at time point (t - 1). That we investigate temporal relationships at four separate occasions over the seven-year period lends considerable weight to our results and the argument that generalised trust is an independent predictor of individual health. However, lack of consensus across a variety of disciplines as to what generalised trust is believed to measure creates ambiguity when attempting to identify possible pathways from higher trust to better health.     

An exploratory multilevel analysis of income,income inequality and self-rated health of the elderly in China

In the last three decades, China has experienced rapid economic development and growing economic inequality, such that economic disparities between rural and urban areas, as well as coastal and interior areas have deepened. Since the late 1990s China has also experienced an ageing population which has attracted attention to the wellbeing of the rapidly growing number of elderly. This research aims to characterise province differences in health and to explore the effects of individual income and economic disparity in the form of income inequality on health outcomes of the elderly. The study is based on the Chinese Longitudinal Healthy Longevity Survey data collected in 2008 for 23 provinces. Multilevel logistic models are employed to investigate the relationship between income, income inequality and self-rated health for the elderly using both individual and province-level variables. Results are presented as relative odds ratios, and for province differentials as Median Odds Ratios. The analysis is deliberately exploratory so as to find evidence of income effects if they exist and particular attention is placed on how province-level inequality (contemporaneous and lagged) may moderate individual relationships. The results show that the health of the elderly is not only affected by individual income (the odds of poor health are 3 times greater for the elderly with the lowest income compared to those at the upper quartile) but also by a small main effect for province-level income inequality (odds ratio of 1.019). There are significant cross-level interactions such that where inequality is high there are greater differences between those with and without formal education, and between men and women with the latter experiencing poorer health.     

An investigation of the longitudinal relationship between neighbourhood income inequality and individual self-rated health in England

There are mixed findings on whether neighbourhood income inequality leads to better self-rated health (SRH) or not. This study considers two hypotheses: individuals living in more unequal neighbourhoods have better SRH and the level of neighbourhood income inequality and its impact on SRH is moderated by household and neighbourhood level income related variables. Data from Waves 8–10 of the UK Household Longitudinal Study for respondents living in England at wave 8 were used. Neighbourhood income inequality was measured using Gini coefficients of household income from the Pay As You Earn and benefits systems for Lower Super Output Areas. Longitudinal ordinal multilevel models predicted self-rated health in 2016–18, 2017–19 and 2019-20 by income inequality and its interaction with household income, neighbourhood median income and neighbourhood deprivation, conditional on individual educational attainment, age, sex, ethnic group, years lived in current residence, region of residence and study wave. There were 24,889 respondents analysed over three waves. SRH was worse for those living in more income equal neighbourhoods. There was no indication that neighbourhood inequality was moderated by household income, neighbourhood median income or neighbourhood deprivation. These findings are in line with the balance of existing evidence and support policy interventions that aim to create mixed communities for the purpose of improving population health.     

Modelling health,income and income inequality: the impact of income inequality on health and health inequality

A framework is developed to analyse the impact of the distribution of income on individual health and health inequality, with individual health modelled as a function of income and the distribution of income. It is demonstrated that the impact of income inequality can generate non-concave health production functions resulting in a non-concave health production possibility frontier. In this context, the impact of different health policies are considered and it is argued that if the distribution of income affects individual health, any policy aimed at equalising health, which does not account for income inequality, will lead to unequal distributions of health. This is an important development given current UK government attention to reducing health inequality.     

Primary care, income inequality, and self-rated health in the United States: a mixed-level analysis.

Using the 1996 Community Tracking Study household survey, the authors examined whether income inequality and primary care, measured at the state level, predict individual morbidity as measured by self-rated health status, while adjusting for potentially confounding individual variables. Their results indicate that distributions of income and primary care within states are significantly associated with individuals' self-rated health; that there is a gradient effect of income inequality on self-rated health; and that individuals living in states with a higher ratio of primary care physician to population are more likely to report good health than those living in states with a lower such ratio. From a policy perspective, improvement in individuals' health is likely to require a multi-pronged approach that addresses individual socioeconomic determinants of health, social and economic policies that affect income distribution, and a strengthening of the primary care aspects of health services.     

Compositional and contextual approaches to the study of health behaviour and outcomes: using multi-level modelling to evaluate Wilkinson's income inequality hypothesis

Much research into health behaviour and outcomes involves evaluating compositional and contextual hypotheses: the former suggest that behaviour/outcomes are a function of the individual's characteristics alone, whereas the latter argue for the importance of contextual/environmental influences. Wilkinson has presented a contextual argument relating inter-country variations in mortality rates to income inequalities; Gravelle has countered this arguing that Wilkinson's findings are a statistical artefact and that a compositional approach, relating mortality to individual income, is sufficient. Discriminating between these two cases requires a methodology combining the two approaches. Multi-level modelling is proposed and applied to two data sets. The results sustain Gravelle's case, emphasising the role of compositional rather than contextual variables in accounting for inter-country variations in health status.     

Metropolitan income inequality and working-age mortality: A cross-sectional analysis using comparable data from five countries

The relationship between income inequality and mortality has come into question as of late from many within-country studies. This article examines the relationship between income inequality and working-age mortality for metropolitan areas (MAs) in Australia, Canada, Great Britain, Sweden, and the United States to provide a fuller understanding of national contexts that produce associations between inequality and mortality. An ecological cross-sectional analysis of income inequality (as measured by median share of income) and working-age (25–64) mortality by using census and vital statistics data for 528 MAs (population >50,000) from five countries in 1990–1991 was used. When data from all countries were pooled, there was a significant relationship between income inequality and mortality in the 528 MAs studied. A hypothetical increase in the share of income to the poorest half of households of 1% was associated with a decline in working-age mortality of over 21 deaths per 100,000. Within each country, however, a significant relationship between inequality and mortality was evident only for MAs in the United States and Great Britain. These two countries had the highest average levels of income inequality and the largest populations of the five countries studied. Although a strong ecological association was found between income inequality and mortality across the 528 MAs, an association between income inequality and mortality was evident only in within-country analyses for the two most unequal countries: the United States and Great Britain. The absence of an effect of metropolitan-scale income inequality on mortality in the more egalitarian countries of Canada. Australia, and Sweden is suggestive of national-scale policies in these countries that buffer hypothetical effects of income inequality as a determinant of population health in industrialized economies.     

A multilevel analysis of the effects of neighbourhood income inequality on individual self-rated health in Hong Kong

We examined the effect on self-rated health of neighbourhood-level income inequality in Hong Kong, which has a high and growing Gini coefficient. Data were derived from two population household surveys in 2002 and 2005 of 25,623 and 24,610 non-institutional residents aged 15 or over. We estimated neighbourhood-level Gini coefficients in each of 287 Government Planning Department Tertiary Planning Units. We used multilevel regression analysis to assess the association of neighbourhood income inequality with individual self-perceived health status. After adjustment for both individual- and household-level predictors, there was no association between neighbourhood income inequality, median household income or household-level income and self-rated health. We tested for but did not find any statistical interaction between these three income-related exposures. These findings suggest that neighbourhood income inequality is not an important predictor of individual health status in Hong Kong.     

Healthcare investment and income inequality

This paper examines how the relative shares of public and private health expenditures impact income inequality. We study a two period overlapping generation's growth model in which longevity is determined by both private and public health expenditure and human capital is the engine of growth. Increased investment in health, reduces mortality, raises return to education and affects income inequality. In such a framework we show that the cross-section earnings inequality is non-decreasing in the private share of health expenditure.We test this prediction empirically using a variable that proxies for the relative intensity of investments (private versus public) using vaccination data from the National Sample Survey Organization for 76 regions in India in the year 1986–87. We link this with region-specific expenditure inequality data for the period 1987–2012. Our empirical findings, though focused on a specific health investment (vaccines), suggest that an increase in the share of the privately provided health care results in higher inequality.     

Socioeconomic inequality in voting participation and self-rated health

OBJECTIVES: This study tested the hypothesis that disparities in political participation across socioeconomic status affect health. Specifically, the association of voting inequality at the state level with individual self-rated health was examined. METHODS: A multilevel study of 279,066 respondents to the Current Population Survey (CPS) was conducted. State-level inequality in voting turnout by socioeconomic status (family income and educational attainment) was derived from November CPS data for 1990, 1992, 1994, and 1996. RESULTS: Individuals living in the states with the highest voting inequality had an odds ratio of fair/poor self-rated health of 1.43 (95% confidence interval [CI] = 1.22, 1.68) compared with individuals living in the states with the lowest voting inequality. This odds ratio decreased to 1.34 (95% CI = 1.14, 1.56) when state income inequality was added and to 1.27 (95% CI = 1.10, 1.45) when state median income was included. The deleterious effect of low individual household income on self-rated health was most pronounced among states with the greatest voting and income inequality. CONCLUSIONS: Socioeconomic inequality in political participation (as measured by voter turnout) is associated with poor self-rated health, independently of both income inequality and state median household income.     

Peripherality, income inequality, and life expectancy: revisiting the income inequality hypothesis

BACKGROUND: Recent criticisms of the income inequality and health hypothesis have stressed the lack of consistent significant evidence for the stronger effects of income inequality among rich countries. Despite such criticisms, little attention has been devoted to the income-based criteria underlying the stratification of countries into rich/poor groups and whether trade patterns and world-system role provide an alternative means of stratifying groups. METHODS: To compare income-based and trade-based criteria, 107 countries were grouped into four typologies: (I) high/low income, (II) OECD membership/non-membership, (III) core/non-core, and (IV) non-periphery/periphery. Each typology was tested separately for significant differences in the effects of income inequality between groups. Separate group comparison tests and regression analyses were conducted for each typology using Rodgers (1979) specification of income, income inequality, and life expectancy. Interaction terms were introduced into Rodgers specification to test whether group classification moderated the effects of income inequality on health. RESULTS: Results show that the effects of income inequality are stronger in the periphery than non-periphery (IV) (-0.76 vs -0.23; P < 0.05). An incremental F-test confirmed significant differences in the coefficient subsets between the two groups (F(2,101) = 6.31; P < 0.01). CONCLUSIONS: Cross-national analyses of income inequality and population health have assumed (i) income differences between countries best capture global stratification and (ii) the negative effects of income inequality are stronger in high-income countries. However, present findings emphasize (i) the importance of measuring global stratification according to trading patterns and (ii) the strong, negative effects of income inequality on life expectancy among peripheral populations.     

No association of income inequality with adult mortality within New Zealand: a multi-level study of 1.4 million 25-64 year olds

STUDY OBJECTIVE: To determine the association of regional income inequality within New Zealand with mortality among 25-64 year olds. DESIGN: Individual census and mortality records were linked over the 1991-94 period. Income inequality (Gini coefficients) and average household income variables were calculated for 35 regions. "Individual level" variables were sex, age, ethnicity, household income, rurality, and small area socioeconomic deprivation. Logistic regression was used for the analyses. Sensitivity analyses for the level of regional aggregation were conducted. PARTICIPANTS: 1.4 million New Zealand census respondents aged 25-64 years followed up for mortality for three years. Main results: Controlling for age, ethnicity, rurality, household income, and regional mean income, there was no association of income inequality with all cause mortality for either men (OR=1.007 for a 0.01 increase in the Gini, 95% confidence intervals 0.989 to 1.024) or women (OR=1.004, 0. 983 to 1.026). By cause of death (cancer, cardiovascular disease, unintentional injury, and suicide) there was some suggestion of a positive association for female unintentional injury (OR=1.068, 0.952 to 1.198) and suicide (OR=1.087, 0.957 to 1.234) but the 95% confidence intervals all included 1.0. Failure to control for ethnicity at the individual level resulted in some association of increasing regional income inequality with increasing mortality risk. Using fewer (n=14) or more (n=73) regional divisions did not substantially change the findings. CONCLUSION: There is no convincing evidence of an association of income inequality within New Zealand with adult mortality. Previous ecological analyses within New Zealand suggesting an association of income inequality with mortality were confounded by ethnicity at the individual level. However, this study does not refute the possibility that income inequality at the national level affects health.     

我国居民与收入相关的健康不平等实证研究

本文利用中国健康与营养调查（CHNS）2006年的调查数据，从定量的角度对我国居民与收入相关的健康不平等进行了分析。本文利用有序Probit模型获得了自评健康数据背后的实际健康得分，在此基础上计算健康集中指数衡量我国居民与收入相关的健康不平等程度。结果表明，我国居民的健康不平等问题较为严重，健康不平等问题在城乡之间和不同经济发展水平地区之间存在着较大的差别。     

Social capital,income inequality and self-rated health in Chita peninsula,Japan: a multilevel analysis of older people in 25 communities

The effect of social capital on one's health has drawn researchers' attention. In East-Asian countries, however, such an effect has been less studied than in Western countries. Mindful of this background, this study aimed to investigate the linkage between social capital and health at the level of a small area in Japan, and also to examine whether social capital mediates the relation between income inequality and health.     

State-level income inequality and individual mortality risk: a prospective, multilevel study

OBJECTIVES: Previous studies have linked state-level income inequality to mortality rates. However, it has been questioned whether the relationship is independent of individual-level income. The present study tests whether state-level income inequality is related to individual mortality risk, after adjustment for individual-level characteristics. METHODS: In this prospective, multilevel study design, the vital status of National Health Interview Survey (NHIS) respondents was ascertained by linkage to the National Death Index, with additional linkage of state-level data to individuals in the NHIS. The analysis included data for 546,888 persons, with 19,379 deaths over the 8-year follow-up period. The Gini coefficient was used as the measure of income inequality. RESULTS: Individuals living in high-income-inequality states were at increased risk of mortality (relative risk = 1.12; 95% confidence interval = 1.04, 1.19) compared with individuals living in low-income-inequality states. In stratified analyses, significant effects of state income inequality on mortality risk were found, primarily for near-poor Whites. CONCLUSIONS: State-level income inequality appears to exert a contextual effect on mortality risk, after income is adjusted for, providing further evidence that the distribution of income is important for health.     

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

Child wellbeing and income inequality in rich societies: ecological cross sectional study .
Pickett K.E. & Wilkinson R.G. ( 2007 ) British Medical Journal , 335 , 1080 – 1085 . DOI: 10.1136/bmj.39377.580162.55.     

Income inequality,area-level poverty,perceived aversion to inequality,and self-rated health in Japan

In this study we conduct a multilevel analysis to investigate the association between regional income inequality and self-rated health in Japan, based on two nationwide surveys. We confirm that there is a significant association between area-level income inequality and individual-level health assessment. We also find that health assessment tends to be more sensitive to income inequality among lower income individuals, and to degree of area-level poverty, than income inequality for the society as a whole. In addition, we examine how individuals are averse to inequality, based on the observed association between inequality and self-rated health.