Estimating the causal effects of income on health: how researchers' definitions of "income" matter.

BACKGROUND: There is a well-established cross-sectional association between income and health, but estimates of the causal effects of income vary substantially. Different definitions of income may lead to substantially different empirical results, yet research is often framed as investigating "the effect of income" as if it were a single, easily definable construct. METHODS/RESULTS: The aim of this paper is to introduce a taxonomy for definitional and conceptual issues in studying individual- or household-level income for health research. We focus on (1) the definition of the income measure (earned and unearned; net, gross, and disposable; real and nominal; individual and household; relative and absolute income) and (2) the definition of the causal contrast (amount, functional form assumptions/transformations, direction, duration of change, and timing of exposure and follow-up). We illustrate the application of the taxonomy to four examples from the published literature. CONCLUSIONS: Quantified estimates of causal effects of income on health and wellbeing have crucial relevance for policymakers to anticipate the consequences of policies targeting the social determinants of health. However, much prior evidence has been limited by lack of clarity in distinguishing between different causal questions. The present framework can help researchers explicitly and precisely articulate income-related exposures and causal questions.

How housing burden damages residents' health: evidence from Chinese cities.

Background: Currently, China is steadily pursuing high-quality development and promoting common prosperity, for which residents' health is a precondition. However, high housing-price-to-income ratios and rent-to-income ratios have already triggered many social problems and have substantially affected people's work and life. It is of practical significance to examine the relationship between housing burden and residents' health. Methods: Combining city-level housing price-to-income ratio data and residents' health data from the China Family Panel Studies, this study employs a binary logit model to investigate the impact and mechanism of housing burden on residents' physical and psychological health. Results: Overall, a 1% increase in the housing-price-to-income ratio leads to a 1.2% decrease in physical health and a 1.9% decrease in psychological health. In terms of different psychological state indicators, a 1% increase in the housing price-to-income ratio leads to a 1.1% increase in depression, 1.1% increase in nervousness, 1.4% increase in relentlessness, 1.4% increase in hopelessness, 1.0% increase in a sense of incapability, and 1.4% increase in meaninglessness. According to mechanistic analyses, a 1% increase in the housing-price-to-income ratio leads to increases of 0.6 and 0.7% in the smoking rate and late sleep rate, respectively, while it leads to a 0.9% decrease in the noon nap rate. Conclusion: A growing housing burden significantly negatively impacts both the physical and psychological health of residents and increases the possibility of negative emotions. Further investigation revealed that the housing burden damages residents' health by increasing their likelihood of smoking and sleeping late and decreasing their likelihood of taking a nap at noon, while exercise alleviates the negative impacts of the housing burden on residents' physical and psychological health. Finally, we also find that housing burdens' impacts on physical and psychological health differ significantly in terms of gender, age, and educational attainment. From the perspective of improving livelihoods, governments should consider the relationship between housing burdens and residents' health when formulating livelihood policies. Location-specific and targeted policies should be followed. Additionally, efforts should be made to promote exercise among citizens.

Preterm Birth, Family Income, and Intergenerational Income Mobility.

Importance: Preterm birth (PTB) has been associated with lower income in adulthood, but associations with intergenerational income mobility and the role of family socioeconomic status (SES) as modifying factor are unclear. Objectives: To assess whether the association between PTB and income differs according to family SES at birth and to assess the association between PTB and intergenerational income mobility. Design, Setting, and Participants: This study comprised a matched cohort of live births in Canada between January 1, 1990, and December 31, 1996, with follow-up until December 31, 2018. Statistical analysis was performed between May 2023 and March 2024. Exposure: Preterm birth, defined as birth between 24 and 37 weeks' gestational age (with gestational age subcategories of 34-36, 32-33, 28-31, and 24-27 weeks) vs early and full term births (gestational age, 37-41 weeks). Main Outcomes and Measures: Associations between PTB and annual adulthood income in 2018 Canadian dollars were assessed overall (current exhange rate: $1 = CAD $1.37) and stratified by family income quintiles, using generalized estimating equation regression models. Associations between PTB and percentile rank change (ie, difference between the rank of individuals and their parents in the income distribution within their respective generations) and upward or downward mobility (based on income quintile) were assessed using linear and multinomial logistic regressions, respectively. Results: Of 1.6 million included births (51.1% boys and 48.9% girls), 6.9% infants were born preterm (5.4% born at 34-36 weeks, 0.7% born at 32-33 weeks, 0.5% born at 28-31 weeks, and 0.2% born at 24-27 weeks). After matching on baseline characteristics (eg, sex, province of birth, and parental demographics) and adjusting for age and period effects, PTB was associated with lower annual income (mean difference, CAD -$687 [95% CI, -$788 to -$586]; 3% lower per year), and the differences were greater among those belonging to families in the lowest family SES quintile (mean difference, CAD -$807 [95% CI, -$998 to -$617]; 5% lower per year). Preterm birth was also associated with lower upward mobility and higher downward mobility, particularly for those born earlier than 31 weeks' gestational age (24-27 weeks: mean difference in percentile rank change, -8.7 percentile points [95% CI, -10.5 to -6.8 percentile points]). Conclusions and Relevance: In this population-based matched cohort study, PTB was associated with lower adulthood income, lower upward social mobility, and higher downward mobility, with greater differences among those belonging to economically disadvantaged families. Interventions to optimize socioeconomic outcomes of preterm-born individuals would need to define target population considering SES.

Reassessing Chronic Strain: A Research Note on Women's Income Dynamics After Divorce and Separation.

The economic consequences of divorce and separation for women are commonly associated with the chronic strain model, according to which women's losses are large and persistent. This research note shifts the focus to a crisis model highlighting women's potential of, and routes to, recovery from initial losses. Drawing on German Socio-Economic Panel data (1984-2021) on women in marital and cohabiting unions (N ∼ 27,000 women, N ∼ 3,400 divorces and separations), we use fixed-effects regression models and event-history models to analyze changes in equivalized monthly household income and poverty risk across the process of divorce and separation. Results show that most women recovered from their initial economic declines. Although initial losses were common and often sizable, large fractions of women eventually returned to or exceeded the household income expected in the absence of divorce and separation. Recovery was facilitated by the "traditional" route of repartnering and the "modern" route of women mobilizing their productive skills. Both routes appeared more important than the absence of barriers, such as children in the household. We conclude that for the majority of women, the economic consequences of divorce and separation are better described as a temporary crisis than as a chronic strain.

Equity implications of tobacco taxation: results from WHO FCTC investment cases.

BACKGROUND: Across time, geographies and country income levels, smoking prevalence is highest among people with lower incomes. Smoking causes further impoverishment of those on the lower end of the income spectrum through expenditure on tobacco and greater risk of ill health. METHODS: This paper summarises the results of investment case equity analyses for 19 countries, presenting the effects of increased taxation on smoking prevalence, health and expenditures. We disaggregate the number of people who smoke, smoking-attributable mortality and cigarette expenditures using smoking prevalence data by income quintile. A uniform 30% increase in price was applied across countries. We estimated the effects of the price increase on smoking prevalence, mortality and cigarette expenditures. RESULTS: In all but one country (Bhutan), a one-time 30% increase in price would reduce smoking prevalence by the largest percent among the poorest 20% of the population. All income groups in all countries would spend more on cigarettes with a 30% increase in price. However, the poorest 20% would pay an average of 12% of the additional money spent. CONCLUSIONS: Our results confirm that health benefits from increases in price through taxation are pro-poor. Even in countries where smoking prevalence is higher among wealthier groups, increasing prices can still be pro-poor due to variable responsiveness to higher prices. The costs associated with higher smoking prevalence among the poor, together with often limited access to healthcare services and displaced spending on basic needs, result in health inequality and perpetuate the cycle of poverty.

Income, aging, and the gendered patterns of wellness: Physical health and subjective well-being in China.

This article investigates the impact of demographic and socioeconomic inequalities on wellness, composed of both physical health and subjective well-being. We examine how gender inequality moderates the joint effects of aging and income on wellness in China. Utilizing generalized linear mixed model (GLMM), we analyze data from the Chinese General Social Survey (CGSS) spanning from 2003 to 2021. Our results reveal that income inequality disproportionately affects physical health among older, underweight, lower-class females; males are more susceptible to negative impacts on subjective well-being, particularly among lower-class, middle-aged males. These gendered patterns are situated in the contemporary Chinese society and are explained in relation to intra-household distributional inequality and the gender role expectations in the Confucian culture. We also discussed the policy implications of how to reduce the gaps in wellness across social classes, age cohorts, and genders.

Associations of occupational physical activity and active transport with depressive symptoms in a middle-income country.

OBJECTIVE: This study investigated the associations of occupational physical activity and active transport with depressive symptoms, stratified by income range, among Brazilian working adults. STUDY DESIGN: This cross-sectional study drew on data from the 2019 Brazilian National Health Survey. METHODS: We used the Patient Health Questionnaire (PHQ-9) to assess depressive symptoms in working adults aged 18-65 years, with physical activities (occupational physical activity and active transport) self-reported through a specially developed questionnaire. Crude and adjusted logistic regression models were fitted. RESULTS: Individuals at the highest level of occupational physical activity (odds ratio [OR] 1.35; 95% confidence interval [95% CI] 1.19-1.53) and at the moderate level of active transport to work (OR 1.66; 95% CI 1.24-2.22) returned increased odds of depressive symptoms as compared with those who were inactive in these domains. Stratified by income group, light active transport to work (OR 0.57; 95% CI 0.34-0.95) in the lower income group (Range 1) was associated with lower odds of depressive symptoms. On the other hand, individuals at the highest level of active transport to work returned higher odds of depressive symptoms in the low- and intermediate-income groups, Ranges 3 and 4 (OR 1.92; 95% CI 1.22-3.00 and OR 2.91; 95% CI 1.71-4.95, respectively). CONCLUSION: Our results suggest that occupational physical activity and active transport may be a risk factor for depressive symptoms. They also point to differences in this relationship by income range. Further studies are needed to pursue the analysis of how specific domains of physical activity contribute to depressive symptoms.

A "food insecurity poverty line" to replace the official threshold in Canadian rural and urban settings? A single-person household perspective.

Household food insecurity is associated with both low income and high cost of living, it is a potentially better measure for consumption compared to income. We use data on food insecurity and income from 10 years of the Canadian Community Health Survey (2007-2017) of single-person households (n = 145,044) to estimate the probability of being food insecure at the Canadian poverty thresholds (Market Basket Measure thresholds, or MBMs), and determine the income required to reach that probability in each MBM region, aggregated by province and rural/urban status. A regression model shows the probability of being food insecure at the MBM is approximately 30% which we call the Food Insecurity Poverty Line (FIPL). The income required to meet the FIPL is substantially different from the MBM, sometimes 1.25 times the MBM. This implies that food insecurity is a potential sentinel measure for poverty.

Nonlinear associations between the ratio of family income to poverty and all-cause mortality among adults in NHANES study.

Socioeconomic status (SES) has been linked to mortality rates, with family income being a quantifiable marker of SES. However, the precise association between the family income-to-poverty ratio (PIR) and all-cause mortality in adults aged 40 and older remains unclear. A cross-sectional study was conducted using data from NHANES III, including 20,497 individuals. The PIR was used to assess financial status, and various demographic, lifestyle, and clinical factors were considered. Mortality data were collected from the NHANES III linked mortality file. The study revealed a non-linear association between PIR and all-cause mortality. The piecewise Cox proportional hazards regression model showed an inflection point at PIR 3.5. Below this threshold, the hazard ratio (HR) for all-cause mortality was 0.85 (95% CI 0.79-0.91), while above 3.5, the HR decreased to 0.66 (95% CI 0.57-0.76). Participants with lower income had a higher probability of all-cause mortality, with middle-income and high-income groups showing lower multivariate-adjusted HRs compared to the low-income group. This study provides evidence of a non-linear association between PIR and all-cause mortality in adults aged 40 and older, with an inflection point at PIR 3.5. These findings emphasize the importance of considering the non-linear relationship between family income and mortality when addressing socioeconomic health disparities.

Height & income: Labor returns of health in Mexico from 2000 to 2018.

Investment in health has been proposed as a mechanism to promote upward social mobility. Previous analyses have reported inconsistent estimates of the returns to investment in health in Mexico based on different models for different years. We aim to estimate returns for Mexico using data from four time points Adult height and labor income are drawn from the periodical national health and nutrition surveys-a group of relatively standardized surveys-that are representative of individuals living in the country in 2000, 2006, 2012 & 2018. These surveys collect anthropometric measurements and information on individuals' labor income. We estimated Mincerian models separately for men and women using OLS, Heckman, instrumental variables, and Heckman with instrumental variables models. Our results indicate significant and positive returns to health for the four surveys, similar in magnitude across years for women and with variations for men. By 2018, returns to health were about 7.4% per additional centimeter in height for females and 9.3% for males. Investments in health and nutrition during childhood and adolescence that increase health capital-measured as adult height-may promote social mobility in Mexico and similar countries to the extent that these investments differentially increase health capital among the poor.

Effects on household income and earnings from chronic kidney disease of non-traditional origins: PREP project findings from Chichigalpa, Nicaragua.

OBJECTIVE: Our purpose with this study is to examine the socioeconomic outcomes associated with chronic kidney disease not related to well-known risk factors (CKDnt) in four communities in Chichigalpa, Nicaragua that are home to a substantial number of sugarcane workers. METHODS: We employed a cluster-based systematic sampling design to identify differences in outcomes between those households affected directly by CKDnt and those that are not. RESULTS: Overall, we find that approximately one-third of households surveyed had a household member diagnosed with CKDnt. 86% of CKDnt households reported that the head of the household had been without work for the last 6 months or more, compared with 53% of non-CKDnt households. Non-CKDnt households took in more than double the earnings income on average than CKDnt households ($C52 835 and $C3120, respectively). Nonetheless, on average, CKDnt households' total income exceeded that of non-CKDnt households due to Nicaragua's national Instituto Nicaraguense de Seguridad Social Social Security payments to CKDnt households, suggestive of a substantial economic burden on the state resulting from the disease. Households headed by widows or widowers who are widowed as a result of CKDnt demonstrate distinct deficits in total income when compared with either non-widowed households or to households widowed by causes other than CKDnt. CONCLUSIONS: Despite strong similarities in terms of demographic characteristics and despite residing in the same communities with similar access to the available resources, households experiencing CKDnt exhibit distinct and statistically significant differences in important socioeconomic outcomes when compared to non-CKDnt households.

Income inequality as a determinant of neonatal mortality in the Americas during 2000-2019: implications for the attainment of Sustainable Development Goal target 3.2.

BACKGROUND: The work of the WHO Commission on the Social Determinants of Health has been fundamental to provide a conceptual framework of the social determinants of health. Based on this framework, this study assesses the relationship of income inequality as a determinant of neonatal mortality in the Americas and relates it to the achievement of the Sustainable Development Goal target 3.2 (reduce neonatal mortality to at least as low as 12 deaths per 1,000 live births). The rationale is to evaluate if income inequality may be considered a social factor that influences neonatal mortality in the Americas. METHODS: Yearly data from 35 countries in the Americas during 2000-2019 was collected. Data sources include the United Nations Inter-agency Group for Child Mortality Estimation for the neonatal mortality rate (measured as neonatal deaths per 1,000 live births) and the United Nations University World Institute for Development Economics Research for the Gini index (measured in a scale from 0 to 100). This is an ecological study that employs a linear regression model that relates the neonatal mortality rate (dependent variable) to the Gini index (independent variable), while controlling for other factors that influence neonatal mortality. Coefficient estimates and their robust standard errors were obtained using panel data techniques. RESULTS: A positive relationship between income inequality and neonatal mortality is found in countries in the Americas during the period studied. In particular, the analysis suggests that a unit increase in a country's Gini index during 2000-2019 is associated with a 0.27 (95% CI [- 0.04, 0.57], P =.09) increase in the neonatal mortality rate. CONCLUSION: The analysis suggests that income inequality may be positively associated with the neonatal mortality rate in the Americas. Nonetheless, given the modest magnitude of the estimates and Gini values and trends during 2000-2019, the findings suggest a potential limited scope for redistributive policies to support reductions in neonatal mortality in the region. Thus, policies and interventions that address higher coverage and quality of services provided by national health systems and reductions in socio-economic inequalities in health are of utmost importance.

Influence of COVID-19 on female sex workers in Dar es Salaam, Tanzania: A mixed-methods analysis.

This study investigates how the landscape of sex work in Dar es Salaam, Tanzania, evolved in the context of the COVID-19 epidemic. Using a mixed-methods approach, the analysis triangulates data from quantitative and qualitative sources to quantify shifts in income, demand, and client frequency and describe female sex workers' perspectives on their work environment. The COVID-19 restrictions introduced in early 2020 resulted in dramatic decreases in sex work income, leading to extreme financial vulnerability, food insecurity, and challenges in meeting other basic needs such as paying rent. However, in a 2021 follow-up survey, sex workers reported the summer of 2021 as a key turning point, with the demand for sex work rebounding to closer to pre-pandemic levels. Notably, despite the average number of unique weekly clients not yet having fully rebounded, by 2021 the price per client and the total monthly sex work income had returned to pre-pandemic levels. This may potentially be explained by an increased number of repeat clients, which represented a larger proportion of all clients during the COVID-19 pandemic.

Association between family income to poverty ratio and nocturia in adults aged 20 years and older: A study from NHANES 2005-2010.

BACKGROUND: Nocturia, the most common lower urinary tract symptom (LUTS), significantly impacts socioeconomic factors and individuals' quality of life and is closely related to many diseases. This study utilized data from NHANES 2005-2010 to explore the relationship between family income to poverty ratio (PIR) and the presence of nocturia symptoms in adults aged 20 or older in the United States. METHODS: Data from the National Health and Nutrition Examination Survey (NHANES) in 2005-2010, including 6,662 adults aged 20 or older, were utilized for this cross-sectional study. The baseline data was used to display the distribution of each characteristic visually. Multiple linear regression and smooth curve fitting were used to study the linear and non-linear correlations between PIR and nocturia. Subgroup analysis and interaction tests were conducted to examine the stability of intergroup relationships. RESULTS: Out of the 6,662 adult participants aged 20 or older, 1,300 households were categorized as living in poverty, 3,671 households had a moderate income, and 1,691 households were classified as affluent. Among these participants, 3,139 individuals experienced nocturia, representing 47.12% of the total, while 3,523 individuals were nocturia-free, constituting 52.88% of the total population. After adjusting for all other covariates, it was found that PIR was significantly negatively correlated with nocturia (OR: 0.875, 95%CI: 0.836-0.916 P<0.0001). This trend persisted when PIR was divided into three groups (PIR <1, PIR 1-4, PIR > 4) or quartiles. There was a non-linear negative correlation between PIR and nocturia. CONCLUSION: Our findings indicated that lower PlR was associated with a higher risk of nocturia in adults aged 20 or older in the United States. These findings highlight the importance of considering socioeconomic factors in preventing and managing nocturia. Nonetheless, further exploration of the causal nexus between these factors was precluded due to the constraints of a cross-sectional design.

Research on the income and expenditure forecast of long-term care insurance fund in Shihezi City based on community care.

Objective: This study forecasts the income and expenditures of the long-term care insurance fund, provides a basis for formulating the raising standard of the long-term care insurance fund, and explores the measures to improve the pilot work of long-term care insurance. Methods: By using the exponential smoothing and ARIMA models to forecast the income and expenditure of the old-age care insurance fund in 2022, the problems existing in the operation of the long-term care insurance fund are discussed. Results: In 2022, the income of the old-age insurance fund was 28.8934 million yuan, and the fund compensation expenditure was 28.4070 million yuan, with a slight balance of the fund. The highest relative errors of income and expenditure forecast models are -2.03% and - 2.76%, respectively. According to the results of fund expenditure, the annual financing standard should be 132.93 yuan/person, and the individual financing standard should be 66.47 yuan/person. Conclusion: Through the integration of personal payment, welfare, sports lottery public welfare income, social donations, and other ways, we can gradually establish a multi-channel risk-sharing financing. We will appropriately raise the standard for individual financing and the annual contribution standard for individuals from 50 yuan to 66.47 yuan. This will promote sustainable development of long-term insurance system.

The Gender Wage Gap Among Early-Career Family Physicians.

PURPOSE: Numerous studies have documented salary differences between male and female physicians. For many specialties, this wage gap has been explored by controlling for measurable factors that influence pay such as productivity, work-life balance, and practice patterns. In family medicine where practice activities differ widely between physicians, it is important to understand what measurable factors may be contributing to the gender wage gap, so that employers and policymakers and can address unjust disparities. METHODS: We used data from the 2017 to 2020 American Board of Family Medicine (ABFM) National Graduate Survey (NGS) which is administered to family physicians 3 years after residency (n = 8608; response rate = 63.9%, 56.2% female). The survey collects clinical income and practice patterns. Multiple linear regression analysis was performed, which included variables on hours worked, degree type, principal professional activity, rural/urban, and region. RESULTS: Although early-career family physician incomes averaged $225,278, female respondents reported incomes that were $43,566 (17%) lower than those of male respondents (P = .001). Generally, female respondents tended toward lower-earning principal professional activities and US regions; worked fewer hours (2.9 per week); and tended to work more frequently in urban settings. However, in adjusted models, this gap in income only fell to $31,804 (13% lower than male respondents, P = .001). CONCLUSION: Even after controlling for measurable factors such as hours worked, degree type, principal professional activity, population density, and region, a significant wage gap persists. Interventions should be taken to eliminate gender bias in wage determinations for family physicians.

Social inequalities in indicators of use of healthcare services by adolescents in Campinas, São Paulo, Brazil.

This study aimed to analyze the prevalence of indicators of use of healthcare services according to sex, income and race/skin color, in adolescents (aged 10-19 years old) based on data from the Health Survey of the Municipality of Campinas (ISACamp), carried out in 2014/2015 in Campinas, São Paulo, Brazil. The chi-square test was used to evaluate the differences between the outcome variables (indicators of use of healthcare service) and sex, income and race/skin color. Adjusted prevalence ratios (PR) were estimated using Poisson multiple regression models. The demand for medical care was high in the last year of the interview (79.2%), mostly attended by the Brazilian Unified National Health System (65.2%), with routine consultations being more prevalent for females (PR = 1.17; 95%CI: 1.01-1.34) and injury for the male population (PR = 0.47; 95%CI: 0.26-0.84). Economic and racial differences were found in the evaluation of the last medical consultation, with a higher prevalence of worse care among those with lower income (PR = 1.46; 95%CI: 1.14-1.87) and black people (PR = 1.27; 95%CI: 1.01-1.61). Inequalities remained for delay or failure to carry out exams (PR = 1.64; 95%CI: 1.02-2.64) and worse quality of dental care (PR = 2.10; 95%CI: 1.38-3.21) in those with lower income. Also, black people had fewer appointments with dentists (PR = 0.90; 95%CI: 0.82-0.99).

Inequality of the crowding-out effect of tobacco expenditure in Colombia.

In recent decades, policy initiatives involving increases in the tobacco tax have increased pressure on budget allocations in poor households. In this study, we examine this issue in the context of the expansion of the social welfare state that has taken place over the last two decades in several emerging economies. This study explores the case of Colombia between 1997 and 2011. In this period, the budget share of the poorest expenditure quintile devoted to tobacco products of smokers' households doubled. We analyse the differences between the poorest and richest quintiles concerning the changes in budget shares, fixing a reference population over time to avoid demographic composition confounders. We find no evidence of crowding-out of education or healthcare expenditures. This is likely to be the result of free universal access to health insurance and basic education for the poor. For higher-income households, tobacco crowds out expenditures on entertainment, leisure activities, and luxury expenditures. This finding should reassure policymakers who are keen to impose tobacco taxes as an element of their public health policy.

In flux: Associations of substance use with instability in housing, employment, and income among young adults experiencing homelessness.

Young adults experiencing homelessness (YAEH) are faced with instabilities in many areas of their lives, including their living situation, employment, and income. Little is known about how the experience of instability in these different domains might be associated with substance use. Leveraging data collected on 276 YAEH in Los Angeles County, regression analyses examine associations between three distinct types of instability (housing, employment, income) and participants' self-reported alcohol use, alcohol consequences, non-cannabis drug use, and substance use symptoms. Results indicated that recent instability in income, employment, and secure housing for those with access to it (but not housing in general or non-secure housing) were significantly associated with greater alcohol/drug use or substance use symptoms. Depression was also found to moderate the association between employment instability and alcohol use. Our findings suggest that efforts to reduce instability in income, employment, and secure housing may have positive benefits for substance using YAEH, especially those with depressive symptoms.