Income inequality and self rated health in Britain

Causal Assessment of Income Inequality on Self-Rated Health and All-Cause Mortality: A Systematic Review and Meta-Analysis

Policy Points Income is thought to impact a broad range of health outcomes. However, whether income inequality (how unequal the distribution of income is in a population) has an additional impact on health is extensively debated. Studies that use multilevel data, which have recently increased in popularity, are necessary to separate the contextual effects of income inequality on health from the effects of individual income on health. Our systematic review found only small associations between income inequality and poor self-rated health and all-cause mortality. The available evidence does not suggest causality, although it remains methodologically flawed and limited, with very few studies using natural experimental approaches or examining income inequality at the national level.

CONTEXT

Whether income inequality has a direct effect on health or is only associated because of the effect of individual income has long been debated. We aimed to understand the association between income inequality and self-rated health (SRH) and all-cause mortality (mortality) and assess if these relationships are likely to be causal.

METHODS

We searched Medline, ISI Web of Science, Embase, and EconLit (PROSPERO: CRD42021252791) for studies considering income inequality and SRH or mortality using multilevel data and adjusting for individual-level socioeconomic position. We calculated pooled odds ratios (ORs) for poor SRH and relative risk ratios (RRs) for mortality from random-effects meta-analyses. We critically appraised included studies using the Risk of Bias in Nonrandomized Studies - of Interventions tool. We assessed certainty of evidence using the Grading of Recommendations Assessment, Development and Evaluation framework and causality using Bradford Hill (BH) viewpoints.

FINDINGS

The primary meta-analyses included 2,916,576 participants in 38 cross-sectional studies assessing SRH and 10,727,470 participants in 14 cohort studies of mortality. Per 0.05-unit increase in the Gini coefficient, a measure of income inequality, the ORs and RRs (95% confidence intervals) for SRH and mortality were 1.06 (1.03-1.08) and 1.02 (1.00-1.04), respectively. A total of 63.2% of SRH and 50.0% of mortality studies were at serious risk of bias (RoB), resulting in very low and low certainty ratings, respectively. For SRH and mortality, we did not identify relevant evidence to assess the specificity or, for SRH only, the experiment BH viewpoints; evidence for strength of association and dose-response gradient was inconclusive because of the high RoB; we found evidence in support of temporality and plausibility.

CONCLUSIONS

Increased income inequality is only marginally associated with SRH and mortality, but the current evidence base is too methodologically limited to support a causal relationship. To address the gaps we identified, future research should focus on income inequality measured at the national level and addressing confounding with natural experiment approaches.

Distribution of self-reported health in India: The role of income and geography

An important new large-scale survey database is brought to bear on measuring and analysing self-reported health in India. The most important correlates are age, income and location. There is substantial variation of health across the 102 'homogeneous regions' within the country, after controlling for household and individual characteristics. Higher income is correlated with better health in only 40% of India. We create novel maps showing regions with poor health, that is attributable to the location, that diverge from the conventional wisdom. These results suggest the need for epidemiological studies in the hotspots of ill-health and in regions where higher income does not correlate with improved health.

Study on the Impact of Income Gap on Health Level of Rural Residents in China

With the rapid development of the social economy, health has increasingly become the focus of attention. Therefore, based on the balanced panel data of the China Household Tracking Survey (CFPS) from 2010 to 2018, the Probit model was used to investigate the impact of the income gap in rural areas on residents' health level, and the relevant influencing mechanism was discussed in this paper. Results: (1) The income gap has a significant negative effect on the health level of rural residents, and the expansion of the income gap will have a more significant impact on the health level of rural residents. (2) The income gap will restrain the health level of rural residents by affecting the family income level and mobility constraints. (3) The restraining effect of the income gap on health formation mainly affects the families of young rural residents, rural male residents, residents with no rental income, and residents with low social capital. This paper analyzes and discusses, from the perspective of income gap, the impact of the income gap on the health status of rural residents in China. Based on the above conclusions, this paper puts forward some feasible suggestions to improve the health level of rural residents.

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.

Income inequality and self-rated health status in Colombia

Background

The negative association between income inequality and health has been known in the literature as the Income Inequality Hypothesis (IIH). Despite the multiple studies examining the validity of this hypothesis, evidence is still inconclusive, and the debate remains unsolved. In addition, relatively few studies have focused their attention on developing or emerging economies, where levels of inequality tend to be the highest in the world. This work examines the statistical association between income inequality and self-rated health status in Colombia, a highly unequal Latin American country.

Methods

To explore whether this association is present in the general population or whether it is only confined to the bottom of the income distribution, we use data from the 2011–2019 National Quality of Life Survey. Multiple probit estimations are considered for testing the robustness of the IIH.

Results

Evidence favouring the IIH was found, even after controlling for individual income levels, average regional income, and socioeconomic characteristics. The link between income inequality and the probability of reporting poor health seems to be present across all income quintiles. However, the magnitude of such association is considerably smaller when using inequality measures with relatively greater sensitivity to income differences among the rich.

Conclusions

The association between regional income inequality and individual's self-rated health status in Colombia is not only confined to low-income individuals but extends across all socioeconomic strata. This association is robust to the income inequality measure implemented, the income-unit of analysis, and changes in the sample. It is suggested that reducing income disparities can potentially contribute to improving individual's health.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12939-022-01659-8.

Poor worker’s long working hours paradox: evidence from the Korea National Health and Nutrition Examination Survey, 2013-2018

Background

Because income and working hours are closely related, the health impact of working hours can vary according to economic status. This study aimed to investigate the relationship between working hours and the risk of poor self-rated health according to household income level.

Methods

We used the data from the Korea National Health and Nutrition Examination Survey VI and VII. The information on working hours and self-rated health was obtained from the questionnaire. After stratifying by household income level, the risk of poor self-rated health for long working hour group (≥ 52 hours a week), compared to the 35–51 working hour group as a reference, were calculated using multiple logistic regression.

Results

Long working hours increased the risk of poor self-rated health in the group with the highest income, but not in the group with the lowest income. On the other hand, the overall weighted prevalence of poor self-rated health was higher in the low-income group.

Conclusions

The relationship between long working hours and the risk of poor self-rated health varied by household income level. This phenomenon, in which the health effects of long working hours appear to diminish in low-income households can be referred to as the ‘poor worker’s long working hours paradox’. Our findings suggest that the recent working hour restriction policy implemented by the Korean government should be promoted, together with a basic wage preservation to improve workers’ general health and well-being.

Factors Associated With Self-Perception in Oral Health of Pregnant Women

Background

Health perception is a subjective predictor of long-term morbidity and mortality. Few studies address the perception that pregnant women have of their oral health.

Objective

The objective of this study was to explore the relationship between socioeconomic factors and self-assessment of oral health in pregnant women from Cali, Colombia.

Method

A cross-sectional study was carried out with a sample of 998 pregnant women, calculated using the formula to estimate a proportion in finite populations, with a confidence level of 95%. A questionnaire was applied for sociodemographic characterization, as well as to enquire about oral health perception, knowledge, and practices of oral health.

Results

The mean age of the surveyed mothers was 24.7, with a standard deviation of 6.1, of which 23.6% were adolescents. The perception they had about their oral health status was considered good by 60.8%. Of the 82.9% who reported having attended dentistry, more than half perceived good oral health. Pregnant women with no history of oral problems, with a perception of medium or high income, and with good oral hygiene practices tend to have a good perception of their oral health.

Conclusion

Pregnant women with no history of oral problems, with a perception of medium or high income, and with good oral hygiene practices tend to have a good perception of their oral health.

Household Income, Pandemic-Related Income Loss, and the Probability of Anxiety and Depression

We use data from the Household Pulse Survey that the US Census Bureau conducted from April 2020 to February 2021 to estimate the probability of symptoms of anxiety and depression among adult Americans. Lack of viable instruments prevent ruling out exogeneity, but the magnitude and strength of association between mental disease and, both, 2019 household income and pandemic-related employment income loss warrant serious attention. Our results stress the importance of policy support to the socially vulnerable in an economic emergency, including cash transfers such as those offered by the 2020 CARES Act or the 2021 America Rescue Plan.

How Does Deprivation Affect Early-Age Mortality? Patterns of Socioeconomic Determinants of Neonatal and Postneonatal Mortality in Bolivia

Three mechanisms related to household living standards might affect early-age mortality: the absolute level of deprivation, its level relative to the average of the community, and the inequality in the distribution of deprivation within communities. A large body of literature has explored the effect of the absolute level of deprivation, but little research has examined the association between relative deprivation and early-age mortality, and findings related to deprivation inequality are inconsistent. Using 2008 Bolivian Demographic and Health Survey data, this study explores patterns of association between the three factors and mortality occurring in the neonatal and postneonatal periods. Because household-level deprivation might capture some unmeasured characteristics at the community level, such as area-specific investments, this study decomposes household-level deprivation into its between- and within-community components. The results show that after possible confounders are controlled for, community-level absolute deprivation is a significant predictor of neonatal and postneonatal mortality. Relative deprivation and deprivation inequality are not associated with early-age mortality. These findings are specific to a context of widespread deprivation and low inequality within communities; the role of the distribution of deprivation might be more important in countries in which basic needs are met within a bigger proportion of the population. This study helps identify crucial sectors of development related to living standards and deprivation inequality in order to tackle neonatal and postneonatal mortality.

Factors Related to Oral Healthcare Service Utilization among Korean Adults Aged 25-79 Years

The factors related to oral healthcare service utilization (OHSU) among Korean adults aged 25-79 years were assessed using the Andersen model with the sixth Korean National Health and Nutrition Examination Survey data. The study included 12,937 participants aged 25-79 years who answered questions on the predisposing, enabling, and need factors related to OHSU at dental clinics within the past 1 year. Age, sex, and education level were selected as predisposing factors; household income, residence region, and national and private health insurance status as enabling factors; and self-perceived oral health, dental pain, chewing status, and discomfort while speaking as need factors. These factors were assessed using multivariable complex logistic regression models. OHSU at dental clinics within the past 1 year was lower among less-educated participants, those with low, middle-low, and middle-high household income levels, rural participants, those benefiting from the Medicaid system, and non-insured participants. OHSU was higher among older participants, those who rated their self-perceived oral health status as bad, those with experience of dental pain, and those who experienced discomfort while chewing and speaking. The need factors were the most influential. Thus, interventions to reduce inequalities in OHSU are required to promote oral health for all.

Economic Inequality in Life Satisfaction and Self-perceived Health in Iranian Children and Adolescents: The CASPIAN IV Study

Background:

The purpose of this study was to assess socioeconomic status (SES) inequality in life satisfaction (LS) and good self-perceived health (SPH) in Iranian children and adolescents.

Methods:

This nationwide study was conducted as part of a fourth national school-based surveillance program performed on 14880 students aged 6–18 years who were living in urban and rural areas of 30 provinces of Iran between 2011 and 2012. Using principle component analysis, the SES of participants was constructed as single variable. SES inequality in LS and good SPH across the SES quintiles was assessed using the concentration index (C) and slope index of inequality (SII). The determinants of this inequality are investigated by the Oaxaca Blinder decomposition method.

Results:

Frequency of LS along with the SES quintiles shifted significantly from 73.28% (95% CI: 71.49, 75.08) in the lowest quintile to 86.57% (95% CI:85.20, 87.93) in the highest SES quintile. Frequency of favorable SPH linearly increased from lowest SES quintile (76.18% (95% CI: 74.45, 77.92)) to highest SES quintile (83.39% (95% CI: 81.89, 84.89)). C index for LS and good SPH was negative, which suggests inequality was in favor of high SES group. SII for LS and SPH was 15.73 (95% CI: 12.10, 19.35) and 8.21 (95% CI: 5.46, 10.96)]. Living area and passive smoking were the most contributed factors in SES inequality of LS. Also passive smoking and physical activity were the most contributed factors in SES inequality of SPH.

Conclusions:

SES inequality in LS and good SPH was in favor of high SES group. These findings are useful for health policies, better programming and future complementary analyses.

Illustrative effects of social capital on health and quality of life among older adult in India: Results from WHO-SAGE India

BACKGROUND

Lacuna in contemporary Indian academic research highlights the need to investigate the component of social capital and health outcome among elderly individuals in Indian context. Study endeavors to investigate prevalence of health indicators: self-rated good health(SRH), functional limitation, depression and quality of life(QoL) and the illustrative effects of social capital on elderly health outcome and QoL.

METHODS

Nationally representative cross-sectional data from WHO Study on global AGEing and adults health (SAGE) India 2007 is used. Individuals aged 50+ are included where logistic regression is used to estimate the effect of social capital along with other co-founders on SRH, functional limitation, and depression. Linear regression model is used to analyse evaluates the impact of social capital with other co-founders on QoL among elderly.

RESULTS

The multivariate analysis shows that SRH is associated with age, female, those having education, higher social-action with strong trust, safety and higher psychological resources. Depression among elderly is significantly related to age, gender, education level, higher wealth, strong sociability. QoL is inversaly related to age, gender, being muslim. A positive association of QoL is observed with higher education, having wealth, and strong social capital component like currently married, civic engagement, social-action, trust solidarity,and strong psychological resources.

CONCLUSION

The paper presents evidence that social capital significantly associated with SRH, lower depression, better functional health and higher quality of life. Hench forth policy makers should construct social policy where elderly feel safe and trusty surrounding, that can involved them into main stream as a productive resource of society.

Does the level of wealth inequality within an area influence the prevalence of depression amongst older people?

This paper considers whether the extent of inequality in house prices within neighbourhoods of England is associated with depressive symptoms in the older population using the English Longitudinal Study of Ageing. We consider two competing hypotheses: first, the wealth inequality hypothesis which proposes that neighbourhood inequality is harmful to health and, second, the mixed neighbourhood hypothesis which suggests that socially mixed neighbourhoods are beneficial for health outcomes. Our results are supportive of the mixed neighbourhood hypothesis, we find a significant association between neighbourhood inequality and depression with lower levels of depression amongst older people in neighbourhoods with greater house price inequality after controlling for individual socio-economic and area correlates of depression. The association between area inequality and depression is strongest for the poorest individuals, but also holds among the most affluent. Our results are in line with research that suggests there are social and health benefits associated with economically mixed communities.

Violence as a public health problem: an ecological study of 169 countries

Individual level risk factors for violence have been widely studied, but little is known about country-level determinants, particularly in low and middle-income countries. We hypothesized that income inequality, through its detrimental effects on social cohesion, would be related to an increase in violence worldwide, and in low and middle-income countries in particular. We examined country-level associations of violence with socio-economic and health-related factors, using crime statistics from the United Nations Office on Drugs and Crime, and indicators from the Human Development Report published by the United Nations Development Programme. Using regression models, we measured relationships between country-level factors (age, education, measures of income, health expenditure, and alcohol consumption) and four violent outcomes (including measures of violence-related mortality and morbidity) in up to 169 countries. We stratified our analyses comparing high with low and middle-income countries, and analysed longitudinal data on homicide and income inequality in high-income countries. In low and middle-income countries, income inequality was related to homicide, robbery, and self-reported assault (all p's < 0.05). In high-income countries, urbanicity was significantly associated with official assault (p = 0.002, β = 0.716) and robbery (p = 0.011, β = 0.587) rates; income inequality was related to homicide (p = 0.006, β = 0.670) and self-reported assault (p = 0.020, β = 0.563), and longitudinally with homicide (p = 0.021). Worldwide, alcohol consumption was associated with self-reported assault rates (p < 0.001, β = 0.369) suggesting public policy interventions reducing alcohol consumption may contribute to reducing violence rates. Our main finding was that income inequality was related to violence in low and middle-income countries. Public health should advocate for global action to moderate income inequality to reduce the global health burden of violence.

Income inequality and mental health--empirical evidence from Australia

The causal association between absolute income and health is well-established; however, the relationship between income inequality and health is not. The conclusions from the received studies vary across the region or country studied and/or the methodology employed. Using the Household, Income and Labour Dynamics in Australia panel survey, this paper investigates the relationship between mental health and inequality in Australia. A variety of income inequality indices are calculated to test both the income inequality and relative deprivation hypotheses. We find that mental health is only adversely affected by the presence of relative deprivation to a very small degree. In addition, we do not find support for the income inequality hypothesis. Importantly, our results are robust to a number of sensitivity analyses.

Why the Scots die younger: synthesizing the evidence

OBJECTIVE

To identify explanations for the higher mortality in Scotland relative to other European countries, and to synthesize those best supported by evidence into an overall explanatory framework.

STUDY DESIGN

Review and dialectical synthesis.

METHODS

Candidate hypotheses were identified based on a literature review and a series of research dissemination events. Each hypothesis was described and critically evaluated in relation to the Bradford-Hill criteria for causation in observational epidemiology. A synthesis of the more convincing hypotheses was then attempted using a broadly 'dialectical' approach.

RESULTS

Seventeen hypotheses were identified including: artefactual explanations (deprivation, migration); 'downstream explanations' (genetics, health behaviours, individual values); 'midstream' explanations (substance misuse; culture of boundlessness and alienation; family, gender relations and parenting differences; lower social capital; sectarianism; culture of limited social mobility; health service supply or demand; deprivation concentration); and 'upstream' explanations (climate, inequalities, de-industrialization, political attack). There is little evidence available to determine why mortality rates diverged between Scotland and other European countries between 1950 and 1980, but the most plausible explanations at present link to particular industrial, employment, housing and cultural patterns. From 1980 onwards, the higher mortality has been driven by unfavourable health behaviours, and it seems quite likely that these are linked to an intensifying climate of conflict, injustice and disempowerment. This is best explained by developing a synthesis beginning from the political attack hypothesis, which suggests that the neoliberal policies implemented from 1979 onwards across the UK disproportionately affected the Scottish population.

CONCLUSIONS

The reasons for the high Scottish mortality between 1950 and 1980 are unclear, but may be linked to particular industrial, employment, housing and cultural patterns. From 1980 onwards, the higher mortality is most likely to be accounted for by a synthesis which begins from the changed political context of the 1980s, and the consequent hopelessness and community disruption experienced. This may have relevance to faltering health improvement in other countries, such as the USA.

Social economic inequalities and mental health II. Methodological aspects and literature review

Summary

Objective - This study provides a framework for mental health inequalities beginners. It describes the methods used to measure socio economic inequalities and the inter-relations with different aspects of mental health: residence, mental health services organisation and main diagnostic categories. Method - Literature electronic-search on Medline, Psyclit, Econlit, Social Science Index and SocioSearch usingand relating the key-words inequalities, deprivation, poverty, socio-economic status, social class, occupational class, mental health for the period 1965-2002 (June). The articles selected were integrated with manual search (publications of the same authors, cross-references, working documents and reports of international andregional organisations). Results - Inequality is not an absolute concept and, mainly, it has been changing during the last years. For example, the integration and re-definition of variables that capture, in simple indices, a complex reality; the accent on social more than on economic aspects; the geo-validity and time-reference of the inequality's indices. Moreover, the inequalities could be the result of individual preferences, in this case, the social selectionand social causation issues will raise the suitability for a public intervention. Conclusions - Up to now, research has been mainly concentrated in describing and measuring health inequalities. For designing effective interventions, policy makers need to ground decisions on health-socioeconomic inequalities explanatory models.

Declaration of Interest

this work was partly funded by the Department of the Public Health Sciences “G. Sanarelli” of the University of Rome “La Sapienza” and the Department of Medicine and Public Health of the University of Verona.

Social economic inequalities and mental health. I. Concepts, theories and interpretations

Summary

Aims – Reconstructing the models used for approaching the inequalities issues in health, idenfiying the most relevant theoretical and conceptual contributions. Method – Literature electronic-search on Medline, Psyclit, Econlit, Social Science Index and SocioSearch using the key-words inequalities, deprivation, poverty, socio-economic status, social class, occupational class, mental health for the period 1965-2002; integrated with manual search. The material was classified according to the conceptual and theoretical interpretative models or to the analyses of the association 'inequalities-health' where health was expressed as mortality, morbidity or services utilisation. Results – Four different interpretative models about the genesis of inequalities were identified. Further theoretical developments overcome the distinction among conceptuals contrapositions selection versus causation, statistic artefactual versus real differences, individual behaviours versus material context. Since the 80's the concept of material deprivation has been enlarged to include social deprivation to explain health inequalities. The social exclusion is related to material deprivation and to social fragility enlarging the traditional aspects of poverty. The theories that better adapt to the psychiatric field are the social selection and social causation. Conclusions – The social exclusion and the new methodologies for measuring the inequalities seems to be an effective way for understanding of the inexplored aspects of the mental health inequalities.

Declaration of Interest: This work was partly funded by the Department of the Public Health Sciences “G. Sanarelli” of the University of Rome “La Sapienza” and the Department of Medicine and Public Health of the University of Verona.

Economic inequality and child stunting in Bangladesh and Kenya: an investigation of six hypotheses

Consistent with the increasing focus on issues of equity in developing countries, I extend the literature analyzing the relationship between economic inequality and individual health to the developing world. Using survey data from Bangladesh and Kenya with economic status measured by a wealth index and with three different geographic definitions of community, I analyze six competing hypotheses for how economic inequality may be related to stunting among children younger than 5 years old. I find little support for the predominant hypothesis that economic inequality as measured by a Gini index is an important predictor of individual health. Instead, I find that the difference between a household's wealth and the mean household wealth in the community is the measure of economic inequality that is most closely related to stunting in these countries. In particular, a 1 standard deviation increase in household wealth relative to the community mean is associated with a 30–32 percent decrease in the odds of stunting in Bangladesh and a 16–21 percent decrease in the odds of stunting in Kenya.

Income inequality and self-rated health status: evidence from the European Community Household Panel

We examine the effect of income inequality on individuals' self-rated health status in a pooled sample of 11 countries, using longitudinal data from the European Community Household Panel survey. Taking advantage of the longitudinal and cross-national nature of our data, and carefully modeling the self-reported health information, we avoid several of the pitfalls suffered by earlier studies on this topic. We calculate income inequality indices measured at two standard levels of geography (NUTS-0 and NUTS-1) and find consistent evidence that income inequality is negatively related to self-rated health status in the European Union for both men and women, particularly when measured at national level. However, despite its statistical significance, the magnitude of the impact of inequality on health is very small.

Self-rated Health, Associated Factors and Diseases: A Community-based Cross-sectional Study of Singaporean Adults Aged 40 Years and Above

Introduction: Subjective indicators of health like self-rated health (SRH) have been shown to be a predictor of mortality and morbidity. We determined the prevalence of poor SRH in Singapore and its association with various lifestyle and socioeconomic factors and disease states. Materials and Methods: Cross-sectional survey by interviewer-administered questionnaire of participants aged 40 years and above. SRH was assessed from a standard question and categorised into poor, fair, good or excellent. Lifestyle factors, socioeconomic factors and presence of disease states were also assessed. Results: Out of 409 participants, 27.6% rated their health as poor or fair, 53.1% as good and 19.3% as excellent. Smaller housing-type (PRR: 1.64, 95% CI: 1.10-2.44) and lack of exercise (PRR: 1.54, 95% CI: 1.06-2.22) were found to be associated with poor SRH. Presence of chronic diseases such as coronary artery disease (PRR: 1.89, 95% CI: 1.13-3.17), diabetes mellitus (PRR: 1.85, 95% CI: 1.18-2.91), history of cancer (PRR: 2.15, 95% CI: 1.05-4.41) and depression (PRR: 1.73, 95% CI: 1.13-2.65) were associated with poor SRH. Conclusion: Prevalence and factors associated with poor SRH in Singapore was comparable to other developed countries. SRH is an important subjective outcome of health and has the potential for wider use in clinical practice in Singapore. Key words: Chronic diseases, Socioeconomic factors, Subjective health indicators

Income, relative income, and self-reported health in Britain 1979-2000

We test the relative income hypothesis that an individual's health depends on the distribution of income in a reference group, as well as on the income of the individual. We use data on 231 208 individuals in Great Britain from 19 rounds of the General Household Survey between 1979 and 2000. Results are insensitive to the measure of self-assessed health used but the sign and significance of the effect of relative income depend on the reference group (national or regional) and the measure of relative income (Gini coefficient, absolute or proportional difference from the reference group mean, Yitzhaki absolute and proportional relative deprivation and affluence). Only one model (relative deprivation measured as income proportional to regional mean income) performs better than the model without relative income and has a positive estimated effect of absolute income on health. In this model the increase in the probability of good health from a ceteris paribus reduction in relative deprivation from the upper quartile to zero is 0.010, whereas an increase in income from the lower to the upper quartile increases the probability by 0.056. While our results provide only very weak support for the relative deprivation hypothesis, the inevitable correlation of measures of individual income and relative deprivation measured by comparing income and incomes in a reference group makes identification of the separate effects of income and relative deprivation problematic.

Income inequality measures

The Gini coefficient has been the most popular method for operationalising income inequality in the public health literature. However, a number of alternative methods exist, and they offer researchers the means to develop a more nuanced understanding of the distribution of income. Income inequality measures such as the generalised entropy index and the Atkinson index offer the ability to examine the effects of inequalities in different areas of the income spectrum, enabling more meaningful quantitative assessments of qualitatively different inequalities. This glossary provides a conceptual introduction to these and other income inequality measures.

What is the relationship between income inequality and health? Evidence from the BHPS

Income inequality hypotheses propose that income differentials and/or income distributions have a detrimental effect on health. This previously well accepted relationship between inequality and health has recently come under scrutiny; some claim that it is a statistical artefact, arguing that aggregate level data are not sophisticated enough to adequately test for (and discriminate between) their existence. Supporters argue that it is a question of estimating the relationship using, amongst other things, an appropriate geographical scale. This paper adds to the debate by estimating the relationship between income inequality and health using individual panel data, exploring the relationship at the regional as well as the national level, while attempting to discriminate between the competing hypotheses. Pooled, random and fixed effects ordered probit models are exploited to estimate the relationship between self-reported health and household income, income inequality and relative income. While the estimating regressions find support for the absolute income hypothesis, there is no support for the income inequality hypothesis or relative income hypothesis, and as such we argue that there is limited evidence of an effect of income inequality on health within Britain.

Path analysis of income, coping and health at the local level in a Canadian context

This article explores the relationships between social, physical, and sociodemographic characteristics and the health status of individuals within four contrasting neighbourhoods in Hamilton, Ontario, using a cross-sectional design. Using data from a telephone survey conducted in 2001 and 2002 of a random sample of adults (1504 respondents, response rate = 60%), path analysis was used to estimate direct and indirect effects of neighbourhood location and satisfaction on health; specifically, the effect of income, coping skills, and neighbourhood satisfaction on self-rated health. Coping was found to be an important mediator between several lifestyle and neighbourhood characteristics and health outcomes. Income and other measures of wealth such as housing tenure, employment, money worries, and lack of money/food bank use were found significant in all health outcomes as well as daily coping ability. Since coping ability was found to be more important for health status than income, policy implications include a greater emphasis on social programmes to assist individuals to manage stress, as well as income support.

Gender, ethnicity, health behaviour & self-rated health in Singapore

Background

Self-rated health and the factors that influence it have never been described in Singapore before. This paper presents a descriptive study of self-rated health in a nationally representative cross-sectional survey of 6236 persons.

Methods

As part of the National Health Surveillance Survey 2001, 6236 subjects aged 18 years and above were interviewed in the homes of participants by trained interviewers. The subjects were asked "In general, how would you rate your health today?", and given 5 possible responses. These were then categorized as "Good" (very good and good) and "Poor" (moderate, bad and very bad) self-rated health. The association of socio-economic and health behaviour risk factors with good self-rated health was studied using univariate and multivariate logistic regression analysis.

Results

Univariate analyses suggest that gender, ethnicity, marital status, education, household income, age, self-reported doctor-diagnosed illnesses, alcohol intake, exercise and BMI are all associated with poor self-rated health. In multivariate regression analyses, gender, ethnicity, household income, age, self-reported illness and current smoking and BMI were associated with poor self-rated health. There are gender differences in the association of various factors such as household income, smoking and BMI to self-rated health.

Conclusion

Socioeconomic factors and health behaviours are significantly associated with self-rated health, and gender differences are striking. We discuss why these factors may impact self-rated health and why gender differences may have been observed, propose directions for further research and comment on the public policy implications of our findings.

Income inequality and population health: A review and explanation of the evidence

Whether or not the scale of a society's income inequality is a determinant of population health is still regarded as a controversial issue. We decided to review the evidence and see if we could find a consistent interpretation of both the positive and negative findings. We identified 168 analyses in 155 papers reporting research findings on the association between income distribution and population health, and classified them according to how far their findings supported the hypothesis that greater income differences are associated with lower standards of population health. Analyses in which all adjusted associations between greater income equality and higher standards of population health were statistically significant and positive were classified as "wholly supportive"; if none were significant and positive they were classified as "unsupportive"; and if some but not all were significant and supportive they were classified as "partially supportive". Of those classified as either wholly supportive or unsupportive, a large majority (70 per cent) suggest that health is less good in societies where income differences are bigger. There were substantial differences in the proportion of supportive findings according to whether inequality was measured in large or small areas. We suggest that the studies of income inequality are more supportive in large areas because in that context income inequality serves as a measure of the scale of social stratification, or how hierarchical a society is. We suggest three explanations for the unsupportive findings reported by a minority of studies. First, many studies measured inequality in areas too small to reflect the scale of social class differences in a society; second, a number of studies controlled for factors which, rather than being genuine confounders, are likely either to mediate between class and health or to be other reflections of the scale of social stratification; and third, the international relationship was temporarily lost (in all but the youngest age groups) during the decade from the mid-1980s when income differences were widening particularly rapidly in a number of countries. We finish by discussing possible objections to our interpretation of the findings.

Income inequality and health in Ontario: a multilevel analysis

OBJECTIVE

To examine the association of income inequality at the public health unit level with individual health status in Ontario.

METHODS

Cross-sectional multilevel study carried out among subjects aged 25 years or older residing in 42 public health units in Ontario. Individual-level data drawn from 30,939 respondents in 1996-97 Ontario Health Survey. Median area income and income inequality (Gini coefficient) calculated from 1996 census. Self-rated health status (SRH) and Health Utilities Index (HUI-3) scores were used as main outcomes.

RESULTS

Controlling for individual-level factors including income, respondents living in public health units in the highest tercile of income inequality had odds ratios of 1.20 (95% CI 1.04 - 1.38) for fair/poor self-rated health, and 1.11 (95% CI 1.01 - 1.22) for HUI score below the median, compared with people living in public health units in the lowest tercile. Controlling further for median area income had little effect on the association.

CONCLUSION

Income inequality was significantly associated with individual self-reported health status at public health unit level in Ontario, independent of individual income.

Self-rated health in Pakistan: results of a national health survey

Background

Self-rated health (SRH) is a robust predictor of mortality. In UK, migrants of South Asian descent, compared to native Caucasian populations, have substantially poorer SRH. Despite its validation among migrant South Asian populations and its popularity in developed countries as a useful public health tool, the SRH scale has not been used at a population level in countries in South Asia. We determined the prevalence of and risk factors for poor/fair SRH among individuals aged ≥15 years in Pakistan (n = 9442).

Methods

The National Health Survey of Pakistan was a cross-sectional population-based survey, conducted between 1990 and 1994, of 18 135 individuals aged 6 months and above; 9442 of them were aged ≥15 years. Our main outcome was SRH which was assessed using the question: "Would you say your health in general is excellent, very good, good, fair, or poor?" SRH was dichotomized into poor/fair, and good (excellent, very good, or good).

Results

Overall 65.1% respondents – 51.3 % men vs. 77.2 % women – rated their health as poor/fair. We found a significant interaction between sex and age (p < 0.0001). The interaction was due to the gender differences only in the ages 15–19 years, whereas poor/fair SRH at all older ages was more prevalent among women and increased at the same rate as it did among men. We also found province of dwelling, low or middle SES, literacy, rural dwelling and current tobacco use to be independently associated with poor/fair SRH.

Conclusion

This is the first study reporting on poor/fair SRH at a population-level in a South Asian country. The prevalence of poor/fair health in Pakistan, especially amongst women, is one of the worst ever reported, warranting immediate attention. Further research is needed to explain why women in Pakistan have, at all ages, poorer SRH than men.

Multivariate models of self-reported health often neglected essential candidate determinants and methodological issues

BACKGROUND AND OBJECTIVE

Self-reported health is an important indicator of overall well-being that may be influenced by diverse parameters. We intended to evaluate the variety of candidate determinants used in models of self-reported health (SRH) and to examine the methodological problems encountered in multivariate models used in recent studies in this field.

STUDY DESIGN AND SETTING

Medline searches identified articles published in 2002 in which SRH was included as an outcome, at least one other variable was used as a determinant of SRH, and the study population was not defined by the presence of specific diseases.

RESULTS

Of 1,991 initially identified reports, 56 were eligible. In 91% of the eligible articles, multivariate models were used. In total, 133 different determinants of SRH were considered (median 7 determinants considered per study with multivariate models). The proportions of studies with problems in multivariate modeling were: overfitting, 10%; nonconformity to a linear gradient, 29%; no report of tests for interactions, 63%; unspecified coding of variables, 49%; and unspecified selection of variables, 29%.

CONCLUSION

Models that try to identify what influences SRH should consider appropriate lists of candidate determinants, with proper attention to methodological aspects of multivariate modeling.

Neighbourhood inequality, neighbourhood affluence and population health

While there is now considerable evidence that the neighbourhood income levels (poverty/affluence) exert an independent effect on health, there is little evidence that neighbourhood income inequality is consequential, net of individual-level socio-economic resources. We show that the usual explanation for the absence of an independent effect of neighbourhood inequality--the assumption of economic homogeneity at the neighbourhood level--cannot account for this result. The authors use hierarchical models that combine individual micro-data from Statistics Canada's 1996/97 National Population Health Survey (NPHS) with neighbourhood and city-level socio-economic characteristics from the 1996 Census of Canada to estimate the effects of neighbourhood affluence and income inequality on self-reported health status. The findings indicate that the negative "ecological" correlation between average neighbourhood health and neighbourhood income inequality is the result not only of compositional differences among individuals but also of contextual neighbourhood effects associated with low and high inequality neighbourhoods.

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.

Exploring the generalisability of the association between income inequality and self-assessed health

A growing between- and within-country literature suggests that the association between income inequality and health reflects individual- or area-level characteristics with which income inequality is associated, rather than the effects of income inequality per se. These studies also suggest that the association between income inequality and health is country-specific. Unresolved methodological issues include the geographical level at which to model the effects of income inequality, and the appropriate statistical methods to use. This study compares the results of single-level and multi-level logistic regression models estimating the association between income inequality and self-assessed health in local authorities in Scotland. The results suggest that there is a significant positive association between income inequality and health across local authorities in Scotland, even after adjusting for individual-level socio-economic status. They also suggest that there is significant local authority-level variation in self-assessed health, but this is small compared to the variation at the individual level. Income and other measures of individuals' socio-economic status are more strongly associated with self-assessed health than income inequality. This study provides further evidence that the income inequality:health association is place-specific. It also suggests that methodological choices regarding the ways of estimating the association between self-assessed health, individual-level socio-economic status and area-level income inequality may not make a substantive difference to the results when contextual effects are small. Further work is required to test the sensitivity of these conclusions to alternative levels of geographical aggregation.

Social inequality and ethnic differences in smoking in New Zealand

This study tests a generalisation of the 'Wilkinson' thesis that the greater a nation's income inequality, the poorer the average national health status. We consider the effect of socio-economic inequality upon ethnic variations in smoking in New Zealand. Analysis of Maori and Pakeha (New Zealanders of European descent) smoking rates from the 1996 Census is conducted for 73 Territorial Local Authority areas in New Zealand, disaggregated by gender and rural-urban location. Partial correlation is used to control for absolute levels of deprivation and examine the independent effect of ethnic social inequality upon smoking rates. The level of social inequality between Maori and Pakeha has an independent effect on Maori smoking rates. Pakeha smoking rates by contrast are more sensitive to variations in absolute rather than relative deprivation. The effect of inequality is greatest for Maori women, especially among urban residents. By contrast, among Maori men the effects are greatest in rural areas. The results provide some qualified support for the Wilkinson thesis and suggest that policies which address fundamental issues of social inequality will play a small, but significant, role in helping to reduce high smoking rates amongst Maori.

Self-esteem, stress and self-rated health in family planning clinic patients

Background

The independent effects of stress on the health of primary care patients might be different for different types of clinic populations. This study examines these relationships in a low-income female population of patients attending a family planning clinic.

Methods

This study investigated the relevance of different sources of personal stress and social support to self-rated health, adjusting for mental health, health behavior and demographic characteristics of subjects. Five hundred women who attended family planning clinics were surveyed and 345 completed the form for a response rate of 72 percent.

Results

Multiple logistic regression analysis revealed that liking oneself was related to good self-rated health (Odds ratio = 7.11), but stress or support from children, parents, friends, churches or spouses were not significant. White non-Hispanic and non-white non-Hispanic respondents had lower odds of reporting good self-rated health than Hispanic respondents (odds ratios were 2.87 and 2.81, respectively). Exercising five or more days per week also was related to good self-rated health. Smoking 20 or more cigarettes per day, and obese III were negatively related to good self-rated health (odds ratios were .19 and .22, respectively with corresponding p-values equal to .0043 and .0332).

Conclusions

Among younger low-income women, addressing low self-esteem might improve health status.

Income, Income Inequality, and Cardiovascular Disease Mortality: Relations Among County Populations of the United States, 1985 to 1994

OBJECTIVES

Despite the major contribution of cardiovascular disease (CVD) to total mortality, and reports demonstrating strong relations between income and CVD, the joint relations of population-level income and income inequality with CVD mortality are not well described. This study was undertaken to describe relations among population-level income, income equality, and mortality due to cardiovascular disease, coronary heart disease, and stroke.

METHODS

County income distributions were determined from 1990 census data, and CVD mortality rates were obtained from the Compressed Mortality File. Relations among income, income inequality, and CVD mortality were examined in stratified and Poisson regression analyses.

RESULTS

County income was inversely related and income inequality was directly related to CVD, coronary heart disease, and stroke mortality. Relations were strongest for stroke. Relations of stroke mortality with income inequality were strongest in low-income populations.

CONCLUSIONS

The CVD mortality experiences of county populations are related to both income and income distribution in a complex, disease-dependent manner. The authors' findings are especially relevant to the Southeast, a region of high income inequality, low income, and high stroke mortality.

Unsafe neighborhoods, social group activity, and self-rated health

The purpose of this project was to assess the importance of stressors and social supports in influencing self-rated health in a community sample so that public health programs could be designed to address the root causes of poor health. The municipal health department in Amarillo, Texas, contracted for a Behavioral Risk Factor Surveillance survey in 2002. The dependant variable for the study was self-rated health. Results suggest that programs targeted at improving neighborhood safety and increasing involvement in organized social groups are needed. Public health agencies may need to collaborate with other governmental agencies in order to craft effective policies.

Is income inequality a determinant of population health? Part 1. A systematic review

This article reviews 98 aggregate and multilevel studies examining the associations between income inequality and health. Overall, there seems to be little support for the idea that income inequality is a major, generalizable determinant of population health differences within or between rich countries. Income inequality may, however, directly influence some health outcomes, such as homicide in some contexts. The strongest evidence for direct health effects is among states in the United States, but even that is somewhat mixed. Despite little support for a direct effect of income inequality on health per se, reducing income inequality by raising the incomes of the most disadvantaged will improve their health, help reduce health inequalities, and generally improve population health.

Income inequality and ischaemic heart disease in Danish men and women

BACKGROUND

It has been hypothesized that areas with an unequal income distribution are less likely to invest in health and more likely to have a social environment that influences the development of ischaemic heart disease (IHD) METHODS: We used pooled data from two cohort studies conducted in Copenhagen to analyse the association between area income inequality and first admission to hospital or death from IHD in women and men while controlling for individual income and other IHD risk factors. A total of 11 685 women and 10 036 men, with initial health examinations between 1964 and 1992, were followed for a median of 13.8 years. Information on median income share at parish and municipality levels was obtained from population registers.

RESULTS

During follow-up 1700 men and 1204 women experienced an IHD event. At parish level income share was inversely associated with an increased risk of IHD in men (hazard ratio [HR](most versus least equal quartile) = 0.85 (95% CI: 0.73-0.98). Among women there was no relation between parish income inequality and IHD. Subject's household income was inversely related to IHD, and when this variable was controlled for, the association between income inequality at parish level and IHD in men attenuated slightly. When behavioural and biological risk factors were entered into the Cox model this relation attenuated further. However, some of these risk factors might mediate rather than confound the effect of income inequality. The association between income inequality at municipality level and IHD was insignificant for men, while in women the relation had a curved shape with those living in the least equal areas having the lowest risk.

CONCLUSIONS

This study provides no clear evidence for an association between income inequality measured at parish or municipality level and IHD in Danish adults. The associations were weak and varied between different strata and geographical levels.