Income Gradient Research Articles

Socioeconomic Inequalities in Frailty Distribution: A Cross-National Comparison of the United States and England.

The objective of this study is to examine differences in socioeconomic gradients (i.e., education, income, and wealth) in frailty by gender in the United States and England. We used harmonized data from the Health and Retirement Study and the English Longitudinal Study of Ageing in 2016. Frailty status was determined from measured and self-reported signs and symptoms in 5 domains: unintentional weight loss, exhaustion, low physical activity, slow walking speed, and weakness. Respondents were classified as robust (no signs or symptoms of frailty), prefrail (signs or symptoms in 1-2 domains), or frail (signs or symptoms in 3 or more domains). Gender-stratified multinomial logistic regression models were used to assess the relationship between educational attainment, household income, and household wealth with the risk of frailty and prefrailty, with and without covariates. We also calculated the slope index of inequalities on the predicted probabilities of frailty by income and wealth quintiles. We found socioeconomic gradients in prefrailty and frailty by education, income, and wealth. Furthermore, the educational gradient in frailty was significantly steeper for U.S. women compared to English women, and the income gradient was steeper for U.S. men and women compared to English men and women. The between-country differences were not accounted for by adjusting for race/ethnicity and behavioral factors. Socioeconomic gradients in prefrailty and frailty differ by country setting and gender, suggesting contextual factors such as cultural norms, healthcare access and quality, and economic policy may contribute to the effect of different measures of socioeconomic status on prefrailty and frailty risk.

Prevalence of Multimorbidity and Chronic Diseases in citizens of the Métis Nation of Ontario

Objective and ApproachPopulation-based analyses of Métis health in Canada are limited. The Métis are a distinct Indigenous people with both First Nation and Euro-Settler ancestry. This study aimed to examine multimorbidity in the Métis Nation of Ontario (MNO) citizens from 2009 to 2019. Registered MNO citizens were linked to Ontario’s administrative health data. An existing data algorithm identified individuals with multimorbidity (2+ chronic conditions) among MNO citizens and the Ontario population aged 18+. Annual prevalence rates of multimorbidity were calculated and rates in the latest year were compared across income quintiles, age, and sex. Results & ConclusionThe prevalence of multimorbidity increased in MNO citizens from 49.2 per 100 (CI: 48.1-50.2) in 2009 to 61.0 per 100 (CI: 59.9-62.1) in 2018. A consistently higher prevalence rate was seen in MNO citizens compared to non-MNO citizens across the entire period. Female MNO citizens had a higher prevalence of multimorbidity compared to males. The prevalence of multimorbidity increased with age in MNO citizens from 40.5 per 100 (CI: 39.1-41.8) in those aged 18 to 44 years up to 91.6 per 100 (CI: 88.4-98.0) in those aged 65 years and older. An income gradient was evident with MNO citizens in the highest income quintile having the lowest prevalence of multimorbidity (57.1 per 100) compared to those in the lowest income quintile (66.3 per 100). ImplicationsUnderstanding the burden of multimorbidity in MNO citizens is essential for the MNO to guide program and policy planning, as well as support decision-making related to resource allocation.

Insect herbivory on Acer rubrum varies across income and urbanization gradients in the D.C. metropolitan area

Urbanization has increased wealth disparity within the United States, impacting the urban landscape and species interactions. In particular, the interactions between street trees and the arthropod communities that live among them may be modified by both human population densities across urban to suburban locations, as well as income levels within these areas. We examined the effect of land use type (urban vs. suburban) and median household income on variation in leaf damage and arthropod abundance of red maples (Acer rubrum) in the District of Columbia metropolitan region. We compared these levels of leaf damage to rates observed in a nearby temperate deciduous forest. We predicted leaf damage would be positively correlated with urbanization (forested < suburban < urban) and negatively correlated with neighborhood income level (low > medium > high). Instead, we observed higher levels of leaf damage on trees in the forest environment compared to the urban and suburban areas. Leaves from urban medium and high-income areas were less likely to exhibit herbivore damage than those from suburban areas. Of the leaves with damage, those in urban high-income and suburban low-income areas exhibited the most leaf area missing. These trends may be related to specific factors associated with urbanization and income level, such as impervious surface coverage and tree coverage. This study highlights differences in biotic interactions across individual neighborhoods and the importance of including socio-economic variables when examining species interactions in urban environments.

Variability in self-reported and biomarker-derived tobacco smoke exposure patterns among individuals who do not smoke by poverty income ratio in the USA

IntroductionTobacco smoke exposure (TSE) among individuals who do not smoke has declined in the USA, however, gaps remain in understanding how TSE patterns across indoor venues—including in homes, cars, workplaces,...

Factors associated with the use of oral health care services among Canadian children and youth.

This study investigates the association between dental insurance, income, and dental care access for Canadian children and youth aged 1 to 17 years. It contributes to a baseline understanding of oral health care use before the implementation of the Canadian Dental Care Plan (CDCP). This study used data from the 2019 Canadian Health Survey on Children and Youth (n=47,347). Descriptive statistics and logistic regression models were employed to assess the association of dental insurance, adjusted family net income, and other sociodemographic factors on oral health care visits and cost-related avoidance of oral health care. A large percentage of children under the age of 5 had never visited a dentist (79.8% of 1-year-olds to 16.4% of 4-year-olds). Overall, 89.6% of Canadian children and youth aged 5 to 17 had visited a dental professional within the past 12 months: 93.1% of those who were insured and 78.5% of those who were uninsured. Insured children and youth had a 4.5% cost-related avoidance of dental care, contrasting with 23.3% for uninsured children and youth. After adjustment for sociodemographic variables, children and youth with dental insurance were nearly three times more likely (odds ratio [OR]: 2.94; 95% confidence interval [CI]: 2.60 to 3.33) to have visited a dental professional in the past 12 months than uninsured children and youth. Having dental insurance (OR: 0.19; 95% CI: 0.16 to 0.21) was protective against barriers to seeing a dental professional because of cost. There was a strong income gradient for both dental service outcomes. The study emphasizes the significant association of dental insurance and access to oral health care for children and youth. It highlights a significant gap between insured and uninsured children and youth and points out the influence of sociodemographic and income factors on this disparity.

Associations between Rat Infestations and Mental Health Vary by Gender, Race, and Income in Chicago.

Rats are an understudied stressor for people in urban environments around the world but the effects may not be distributed equally among residents. In this study, we examined associations between residential rat sightings and mental health in Chicago, where rat complaints are the highest of any American city. We examined how this relationship varied by frequency of rat sightings, race, ethnicity, income, home ownership, and gender and explored potential psychosocial pathways (e.g., feelings about the home) between rat sightings and mental distress. We conducted a randomized household survey along an income gradient in 2021 and asked about depressive symptoms in the past week (i.e., Center for Epidemiologic Studies Depression scale), frequency of rat sightings in/around the home, perceptions of rats, neighborhood conditions, and socio-demographic characteristics. We used logistic regression to assess relationships among these variables for our entire sample and for specific demographics using stratified models. Respondents (n = 589; 409 complete cases) who saw rats in/around the home daily/almost daily had 5.5 times higher odds of reporting high depressive symptoms relative to respondents who saw rats less frequently after accounting for socio-demographics and neighborhood conditions. This relationship was significant for men and respondents with lower incomes or race or ethnicity other than white. Our results show that rat infestations should be considered a threat to mental health among urban residents. Increased mental health support for residents living in rat-infested housing may improve public health in cities.

Risk of premature mortality due to smoking, alcohol use, obesity and physical activity varies by income: A population-based cohort study

BackgroundPremature deaths are a strong population health indicator. There is a persistent and widening pattern of income inequities for premature mortality. We sought to understand the combined effect of health behaviours and income on premature mortality in a large population-based cohort. MethodsWe analyzed a cohort of 121,197 adults in the 2005–2014 Canadian Community Health Surveys, linked to vital statistics data to ascertain deaths for up to 5 years following baseline. Information on household income quintile and mortality-relevant risk factors (smoking status, alcohol use, body mass index (BMI), and physical activity) was captured from the survey. Hazard ratios (HR) for combined income-risk factor groups were estimated using Cox proportional hazards models. Stratified Cox models were used to identify quintile-specific HR for each risk factor. ResultsFor each risk factor, HR of premature mortality was highest in the lowest-income, highest-risk group. Additionally, an income gradient was seen for premature mortality HR for every exposure level of each risk factor. In the stratified models, risk factor HRs did not vary meaningfully between income groups. All findings were consistent in the unadjusted and adjusted models. ConclusionThese findings highlight the need for targeted strategies to reduce health inequities and more careful attention to how policies and interventions are distributed at the population level. This includes targeting and tailoring resources to those in lower income groups who disproportionately experience premature mortality risk to prevent further widening health inequities.

Has it always paid to be rich? Income and cause-specific mortality in southern Sweden 1905–2014

Socio-economic differences in mortality are among the most pervasive characteristics of Western societies. While the mortality gradient by income is well established for the period after 1970, knowledge about the origins of this gradient is still rudimentary. We analyse the association between income and cause-specific adult mortality during the period 1905–2014 in an area of southern Sweden, using competing-risk hazard models with individual-level longitudinal data for over 2.2 million person-years and over 35,000 deaths. We find that the present-day income gradient in adult mortality emerged only in the period after the Second World War and did so for the leading causes of death and for men and women largely simultaneously.

Socioeconomic mortality differences during the Great Influenza in Spain

Despite being one of the deadliest viruses in history, there is limited information on the socioeconomic factors that affected mortality rates during the Great Influenza Pandemic. In this study, we use occupation-province level data to investigate the relationship between influenza excess mortality rates and occupation-related status in Spain. We obtain three main results. Firstly, individuals in low-income occupations experienced the highest excess mortality, pointing to a notable income gradient. Secondly, professions that involved more social interaction were associated with a higher excess of mortality, regardless of income. Finally, we observe a substantial rural mortality penalty, even after controlling for income-related occupational groups. Based on this evidence, it seems that the high number of deaths was caused by not self-isolating. Some individuals did not quarantine themselves because they could not afford to miss work. In rural areas, home confinement was likely more limited because their inhabitants did not have immediate access to information about the pandemic or fully understand its impact due to their limited experience handling influenza outbreaks.

Grandparental income and adverse neonatal outcomes in Finland in 2000 − 2015

Abstract Background Pre-term births and other adverse neonatal outcomes are a major burden to healthcare systems, and they also contribute to long-term health problems. Socioeconomic inequalities in these outcomes are well-documented, but whether grandparental characteristics influence them over and above parental characteristics remains unclear. Methods We used population register data on all singleton children of non-migrant origin, born in Finland in 2000 − 2015 (n = 341,715), linked to their both biological parents and all four grandparents, including an indicator for deceased kin members. We examined whether grandparental income predicted grandchildren's neonatal outcomes (preterm birth, low birth weight, small for gestational age, congenital malformations) in addition to parental income, once accounting for sociodemographic family characteristics such as parental age, parity, education, family structure, and maternal smoking. Results We found a consistent association between lower income and adverse neonatal outcomes, for both mothers and fathers, as well as maternal and paternal grandparents. The gradient was stronger among young mothers (under age 25), e.g., the prevalence of being born small for gestational age was 11% for the highest parental or grandparental income quintile, while for the lowest it ranged from 13 to 15%. Overall, the income gradients clearly attenuated in adjusted models, but remained. Preliminary results suggest grandparental characteristics mainly influence grandchild outcomes through the middle generation, but depending on the outcome, partly independent associations remain. Conclusions Even in the context of a Nordic welfare state, offspring of lower income grandparents are at higher risk of adverse neonatal outcomes, particularly when born to young mothers. This influence mainly, but not fully, passes through the parental generation, suggesting more support should be offered to expecting parents with low income and from disadvantaged backgrounds. Key messages • Lower grandparental income predicts higher risk of adverse neonatal outcomes, particularly when born to young mothers. • Expecting parents with low income and disadvantaged family background should be supported to reduce adverse neonatal outcomes.

Waves of inequality: Income differences in intensive care due to Covid-19 in Sweden

Abstract Background Individuals in lower social strata were overall more likely to develop severe Covid-19 during the pandemic. However, specific conditions in terms of preparedness, knowledge and the properties of the virus itself changed during the course of the pandemic. Socioeconomic inequalities in Covid-19 may therefore shift over time. This study examines the relationship between income and intensive care (ICU) episodes due to Covid-19 in Sweden during three distinct waves. Methods This study uses Swedish register data on the total adult population and estimate the relative risk (RR) of ICU episodes due to Covid-19 by income quartile for each month between March 2020 and May 2022, and for each wave, using Poisson regression analyses. Results The first wave had modest income-related inequalities, while the second wave had a clear income gradient, with the lowest income quartile having an increased risk compared to the high-income group (RR: 1·55 [1·36 - 1·77]). In the third wave, the overall need for ICU decreased, but relative risks increased, particularly the top and bottom income quartiles (RR: 3·72 [3·50 - 3·96]). Inequalities in the third wave were partly explained by differential vaccination coverage by income quartile, although substantial inequalities remained after adjustment for vaccination status (RR: 2·39 [2·20 - 2·59]). Conclusions The study highlights the importance of considering the changing mechanisms that connect income and health during a novel pandemic. Health inequalities per income group increased for each subsequent wave. As the aetiology of Covid-19 became better understood those with more resources could better protect themselves from infection. Understanding the social dynamic of infectious diseases can help prepare for possible future pandemics. Key messages • Health inequalities in severe covid-19 infections increased as the pandemic progressed. • Understanding the social dynamic of infectious diseases can help prepare for possible future pandemics.

Using socioeconomic disparities in ACS mortality to identify opportunities for better cardiac care

Abstract Background Though cardiac care in acute coronary syndrome (ACS) should be equitable, socioeconomic disparities in associated mortality persist. In this study we ask if problems in provision of cardiac care could be pinpointed by examining these disparities in mortality between different time-points of ACS care. Thus, we assessed how socioeconomic disparities in one-year coronary heart disease (CHD) mortality emerged in Finland both outside hospital and in three consecutive time-points after ACS hospitalisation. Methods We obtained individual data of incident ACS hospitalisation for those aged ≥40 in 2013-2017 from national hospitalisation registers. Respective data for CHD mortality, education, income, living alone and travel time to hospital were obtained from Statistics Finland and from Digiroad database. Comorbidity was measured with Charlson index. Two-level Poisson multilevel models provided incidence rate ratios (IRRs) separately in total CHD mortality (including prehospital deaths) and by the time of death after ACS hospitalisation (within 1-7 days, 8-28 d and 29-365 d). Variation between hospital districts was adjusted for with random effects. Results Of 31,902 CHD deaths 74.9% occurred prehospital, 9.0% within 1-7 d, 6.2% within 8-28 d and 9.9% within 29-365 d of ACS hospitalisation. IRRs for living alone were 1.25-fold (CI95% 1.22-1.29) for total CHD mortality but varied between 0.95-1.05-fold after ACS hospitalisation. A clear income gradient emerged favouring higher quintiles. In the highest quintile IRRs were constantly 0.53-0.56-fold (CI95% 0.43-0.73) to those of the lowest quintile. In other quintiles income disparities were fewer, especially within 1-7 d. Conclusions Though socioeconomic disparities in CHD mortality persisted throughout cardiac care, more focus should be given especially to subacute care and rehabilitation of vulnerable groups. Improving early identification of ACS in those living alone offers opportunities to decrease excess CHD mortality. Key messages • A detailed analysis of socioeconomic disparities in one-year mortality after acute coronary syndrome event can provide opportunities for improving provision of cardiac care. • More focus should be given especially to subacute cardiac care and rehabilitation of vulnerable populations, as well as to early identification of acute coronary syndrome events in those living alone.

Child mental health and income gradient from early childhood to adolescence: Evidence from the UK

BackgroundChildren from low income families are likely to have poorer mental health than their more affluent peers. However, it is unclear how this association varies at different developmental stages and what the potential underpinning mechanisms are. This study investigates the relationship between family income and mental health problems from early childhood to adolescence in the UK, and examines the potential mediating role of family-related factors over time. MethodsData were drawn from the UK Millennium Cohort Study at ages 3, 5, 7, 11, 14 and 17 years. Child mental health was measured by the Strengths and Difficulties Questionnaire Total Difficulties Score, and the Internalising and Externalising subscales. Family income was operationalised as permanent income. Cross-sectional analyses were conducted at each age to examine the association between income and mental health problems, and to examine potential mechanisms based on the Parental Stress and Parental Investment theories. ResultsThe samples included 8096 children aged up to 14 years, of which 5667 remained in the study at age 17. Results indicated a statistically significant association between lower family income and poorer mental health in all age groups after adjusting for confounding factors. The strength of the association was reduced after adjustment for Parental Stress and Parental Investment factors, with the larger attenuation driven by Parental Stress factors in most cases. Fully adjusted models suggested an increased independent association between maternal psychological distress and children's mental health as children grew older. ConclusionsWhile lower family income is associated with a child's poorer mental health, much of this association is explained by other factors such as maternal psychological distress, and therefore the direct association is relatively small. This suggests that policies targeting income redistribution may reduce child mental health problems, and also benefit the wider family, reducing the prevalence of other associated risk factors.

High-status individuals are held to higher ethical standards

Although there is evidence for the generosity of high-status individuals, there seems to be a strong perception that the elites are selfish and contribute little to others’ welfare, and even less so than poorer people. We argue that this perception may derive from a gap between normative and empirical expectations regarding the behavior of the elites. Using large-scale survey experiments, we show that high-status individuals are held to higher ethical standards in both the US and China, and that there is a strong income gradient in normatively expected generosity. We also present evidence for a gap between people’s normative expectations of how the rich should behave, and their empirical expectations of how they actually do: empirical expectations are generally lower than both normative expectations and actual giving.

Combined influence of immigration status and income on cervical cancer screening uptake

The regular performance of Pap tests for cervical cancer screening reduces this disease's incidence and mortality. Income inequalities have been reported for this screening, partly because in some countries women must advance or even pay out-of-pocket costs. Because immigrant status is also associated with low Pap test uptake, we aimed to analyze the combined impact of immigrant status and low income on cervical cancer underscreening. This study, based on the French CONSTANCES cohort, uses data from the cohort questionnaires and linked health insurance fund data about Pap test reimbursement. To measure income inequalities in screening, we calculated a Slope Index of Inequality (SII) by linear regression, taking into account the migration status of participants. The majority of the 70,614 women included in the analysis were not immigrants (80.2%), while 12.9% were second-generation immigrants, and 6.9% first-generation immigrants. The proportion of underscreening increased with immigrant status, from 19.5% among nonimmigrants to 23.6% among the second generation, and 26.5% among the first (P < 0.01). The proportion of underscreening also increased as income level decreased. The income gradient rose significantly from 14% among nonimmigrants to 21% in second-generation immigrants and 19% in the first generation (P < 0.01). Among first-generation migrants, the shorter the duration of residence, the higher the SII. Women who are first- or second-generation immigrants are simultaneously underscreened and subject to a more unfavorable economic gradient than native French women born to native French parents. The accumulation of several negative factors could be particularly unfavorable to screening uptake.

Income mortality paradox by immigrants’ duration of residence in Sweden: a population register-based study

BackgroundStudies have shown that, compared with the general native population, immigrants display weaker or absent income gradients in mortality. The aim of this study is to examine the extent to...

Socio-economic distribution of modifiable risk factors for cardiovascular diseases: An analysis of the national longitudinal ageing study in India

The association of socioeconomic status (SES) with modifiable risk factors for cardiovascular diseases (CVDs) is unclear in developing nations. We studied SES variations in major risk factors and their percentage distribution for adults aged 45 years or above in India. Using individual records of 59,672 individuals aged 45 years or above from the Longitudinal Ageing Study in India Wave 1 (cross-sectional study design), 2017–18, we chart age-and-sex-adjusted prevalence of clinical risk factors such as measured high blood pressure, hypertension, overweight, obesity, central adiposity and self-reported high blood glucose; and lifestyle risk factors such as excessive use of alcohol, current use of smoking and smokeless tobacco and physical inactivity across SES variables of education, quintiles of mean per capita expenditure and social caste. Multivariable analysis was used to explore the SES gradient of risk factors. The sample used in the study is predominantly rural (69.9%), illiterate (50.7%), has more females (54.2%), and belongs to other backward classes (45.6%). Prevalence of high blood pressure, overweight, obesity, central adiposity, high blood glucose, and physical inactivity increased; and excessive alcohol consumption and current use of smoking/smokeless tobacco decreased with income, education, and social caste. However, no significant income gradient was noted for lifestyle risk factors except the use of smokeless tobacco. The income gradient was largest for central adiposity (waist-circumference) with a difference of 23.4 percentage points as it increased from 38.7% among the poorest to 62.1% among the richest. The major burden of CVDs risk factors among older adults aged 45+ years falls among high SES.

Income is more protective against pain in more equal countries

It is empirically well-established that the rich suffer less pain on average than the poor. However, much less is known about the factors that moderate the size of the income gradient of pain. Using data from over 1 million adults from 127 countries worldwide, this article conducts a systematic test on whether income inequality moderates the pain gap between the rich and the poor. While pain is negatively associated with income in all but one country, there is strong evidence to suggest that an increase in income is much more protective against pain in countries where the income distribution is relatively more equal. The results are robust to using different measures of income inequality, removing outliers, and accounting for country and year fixed effects. We explain our results through the lens of income rank effects on health outcomes. Overall, our findings suggest that pain-reducing policies through income redistribution may need to take income inequality into consideration when evaluating their effectiveness.

Towards an encompassing concept of remittance in the digital era: Assessing the role of formal banking and mobile money accounting in its spatial flow

Drawing from capital mobility theory, this article adopts an encompassing view on remittance that covers both domestic and international financial transfers, to retrospectively explore and evaluate the relative influences of formal banking (FB) and mobile money accounting (MMA) on the extensive supply of remittances from individuals living within the economic community of the West African states (ECOWAS), during the COVID-19 pandemic. To that end, the study uses random utility maximization to model ECOWAS level data extracted from the 2021 Global Findex Survey. The results show that FB and MMA had respectively 12.2% and 54.5% positive impacts on the marginal utilities (MUs) individuals derive from supplying remittances. The comparative evaluation of the two remittance channels suggested that FB and MMA were neither substitutes, nor complements into the individual’s extensive supply function of remittances within ECOWAS. However, MMA was found to be 4.47 times more effective than FB, at driving outbound remittance behavior. Additionally, the findings revealed a significant income gradient in outbound remittance behavior; as well as highlighting a 22.4% gender based gradient in remittance sending in favor of females; and a 6.4% regional gradient favoring urban residents. Moreover, the econometric findings suggested that expending financial inclusion through easing access to key financial products and services; as well as government welfare programs, and employment income, significantly increased the likelihood of remittance sending within the ECOWAS bloc. Hence, important implications for endogenous regional growth and future research are discussed.

Differences in site-specific cancer incidence by individual- and area-level income in Canada from 2006 to 2015.

Income, a component of socioeconomic status, influences cancer risk as a social determinant of health. We evaluated the independent associations between individual- and area-level income and site-specific cancer incidence in Canada. We used data from the 2006 and 2011 Canadian Census Health and Environment Cohorts, which are probabilistically linked datasets constituted by 5.9 million and 6.5 million respondents of the 2006 Canadian long-form census and 2011 National Household Survey, respectively. Individuals were linked to the Canadian Cancer Registry through 2015. Individual-level income was derived using after-tax household income adjusted for household size. Annual tax return postal codes were used to assign area-level income quintiles to individuals for each year of follow-up. We calculated age-standardized incidence rates (ASIR) and rate ratios for cancers overall and by site. We conducted multivariable negative binomial regression to adjust these rates for other demographic and socioeconomic variables. Individuals of lower individual- and area-level income had higher ASIRs compared to those in the wealthiest income quintile for head and neck, oropharyngeal, esophageal, stomach, colorectal, anal, liver, pancreas, lung, cervical and kidney and renal pelvis cancers. Conversely, individuals of wealthier individual- and area-level income had higher ASIRs for melanoma, leukemia, Hodgkin's lymphoma, non-Hodgkin's lymphoma, breast, uterine, prostate and testicular cancers. Most differences in site-specific incidence by income quintile remained after adjustment. Although Canada's publicly funded healthcare system provides universal coverage, inequalities in cancer incidence persist across individual- and area-level income gradients. Our estimates suggest that individual- and area-level income affect cancer incidence through independent mechanisms.