Poverty or income inequality as predictor of mortality: longitudinal cohort study.

OBJECTIVE: To determine the effect of inequality in income between communities independent of household income on individual all cause mortality in the United States. DESIGN: Longitudinal cohort study. SUBJECTS: A nationally representative sample of 14,407 people aged 25-74 years in the United States from the first national health and nutrition examination survey. SETTING: Subjects were followed from initial interview in 1971-5 until 1987. Complete follow up information was available for 92.2% of the sample. MAIN OUTCOME MEASURES: Relation between both household income and income inequality in community of residence and individual all cause mortality at follow up was examined with Cox proportional hazards survival analysis. RESULTS: Community income inequality showed a significant association with subsequent community mortality, and with individual mortality after adjustment for age, sex, and mean income in the community of residence. After adjustment for individual household income, however, the association with mortality was lost. CONCLUSIONS: In this nationally representative American sample, family income, but not community income inequality, independently predicts mortality. Previously reported ecological associations between income inequality and mortality may reflect confounding between individual family income and mortality.     

Relations of income inequality and family income to chronic medical conditions and mental health disorders: national survey

ObjectivesTo analyse the relation between geographical inequalities in income and the prevalence of common chronic medical conditions and mental health disorders, and to compare it with the relation between family income and these health problems.Design Nationally representative household telephone survey conducted in 1997-8.Setting 60 metropolitan areas or economic areas of the United States.Participants 9585 adults who participated in the community tracking study.Results A strong continuous association was seen between health and education or family income. No relation was found between income inequality and the prevalence of chronic medical problems or depressive disorders and anxiety disorders, either across the whole population or among poorer people. Only self reported overall health, the measure used in previous studies, was significantly correlated with inequality at the population level, but this correlation disappeared after adjustment for individual characteristics.Conclusions This study provides no evidence for the hypothesis that income inequality is a major risk factor for common disorders of physical or mental health.

What is already known on this topic

Several studies have found a relation between income inequality and self reported health or mortality

What this study adds

There is a strong social gradient in health, as measured by the prevalence of chronic medical conditions and specific mental health disorders, by income or educationNo such association is seen between income inequality and health     

Relation between fractures and mortality: results from the Canadian Multicentre Osteoporosis Study

Background

Fractures have largely been assessed by their impact on quality of life or health care costs. We conducted this study to evaluate the relation between fractures and mortality.

Methods

A total of 7753 randomly selected people (2187 men and 5566 women) aged 50 years and older from across Canada participated in a 5-year observational cohort study. Incident fractures were identified on the basis of validated self-report and were classified by type (vertebral, pelvic, forearm or wrist, rib, hip and “other”). We subdivided fracture groups by the year in which the fracture occurred during follow-up; those occurring in the fourth and fifth years were grouped together. We examined the relation between the time of the incident fracture and death.

Results

Compared with participants who had no fracture during follow-up, those who had a vertebral fracture in the second year were at increased risk of death (adjusted hazard ratio [HR] 2.7, 95% confidence interval [CI] 1.1–6.6); also at risk were those who had a hip fracture during the first year (adjusted HR 3.2, 95% CI 1.4–7.4). Among women, the risk of death was increased for those with a vertebral fracture during the first year (adjusted HR 3.7, 95% CI 1.1–12.8) or the second year of follow-up (adjusted HR 3.2, 95% CI 1.2–8.1). The risk of death was also increased among women with hip fracture during the first year of follow-up (adjusted HR 3.0, 95% CI 1.0–8.7).

Interpretation

Vertebral and hip fractures are associated with an increased risk of death. Interventions that reduce the incidence of these fractures need to be implemented to improve survival.Osteoporosis-related fractures are a major health concern, affecting a growing number of individuals worldwide. The burden of fracture has largely been assessed by the impact on health-related quality of life and health care costs.^1,2 Fractures can also be associated with death. However, trials that have examined the relation between fractures and mortality have had limitations that may influence their results and the generalizability of the studies, including small samples,^3,4 the examination of only 1 type of fracture,^4–10 the inclusion of only women,^8,11 the enrolment of participants from specific areas (i.e., hospitals or certain geographic regions),^{3,4,7,8,10,12} the nonrandom selection of participants^3–11 and the lack of statistical adjustment for confounding factors that may influence mortality.^3,5–7,12We evaluated the relation between incident fractures and mortality over a 5-year period in a cohort of men and women 50 years of age and older. In addition, we examined whether other characteristics of participants were risk factors for death.     

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

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

An empirical demonstration of risk-sensitive foraging preferences

We report laboratory experiments with yellow-eyed juncos (Junco phaeonotus) revealing that the birds' foraging preferences for variable rewards respond not only to the mean, but also the variance, of food rewards. The nature of their preferences for variable rewards is related to their expected daily energy budget. We summarize the birds' preferences in utility functions for energetic rewards. Since mean reward size is inadequate to predict their behaviour, we believe that foraging models should consider environmental stochasticity and an animal's response to this variation.     

Inequality in income and mortality in the United States: analysis of mortality and potential pathways.

OBJECTIVE--To examine the relation between health outcomes and the equality with which income is distributed in the United States. DESIGN--The degree of income inequality, defined as the percentage of total household income received by the less well off 50% of households, and changes in income inequality were calculated for the 50 states in 1980 and 1990. These measures were then examined in relation to all cause mortality adjusted for age for each state, age specific deaths, changes in mortalities, and other health outcomes and potential pathways for 1980, 1990, and 1989-91. MAIN OUTCOME MEASURE--Age adjusted mortality from all causes. RESULTS--There was a significant correlation (r = -0.62 [corrected], P < 0.001) between the percentage of total household income received by the less well off 50% in each state and all cause mortality, unaffected by adjustment for state median incomes. Income inequality was also significantly associated with age specific mortalities and rates of low birth weight, homicide, violent crime, work disability, expenditures on medical care and police protection, smoking, and sedentary activity. Rates of unemployment, imprisonment, recipients of income assistance and food stamps, lack of medical insurance, and educational outcomes were also worse as income inequality increased. Income inequality was also associated with mortality trends, and there was a suggestion of an impact of inequality trends on mortality trends. CONCLUSION--Variations between states in the inequality of the distribution of income are significantly associated with variations between states in a large number of health outcomes and social indicators and with mortality trends. These differences parallel relative investments in human and social capital. Economic policies that influence income and wealth inequality may have an important impact on the health of countries.     

The association between temperature and mortality in tropical middle income Thailand from 1999 to 2008

We have investigated the association between tropical weather condition and age-sex adjusted death rates (ADR) in Thailand over a 10-year period from 1999 to 2008. Population, mortality, weather and air pollution data were obtained from four national databases. Alternating multivariable fractional polynomial (MFP) regression and stepwise multivariable linear regression analysis were used to sequentially build models of the associations between temperature variable and deaths, adjusted for the effects and interactions of age, sex, weather (6 variables), and air pollution (10 variables). The associations are explored and compared among three seasons (cold, hot and wet months) and four weather zones of Thailand (the North, Northeast, Central, and South regions). We found statistically significant associations between temperature and mortality in Thailand. The maximum temperature is the most important variable in predicting mortality. Overall, the association is nonlinear U-shape and 31 °C is the minimum-mortality temperature in Thailand. The death rates increase when maximum temperature increase with the highest rates in the North and Central during hot months. The final equation used in this study allowed estimation of the impact of a 4 °C increase in temperature as projected for Thailand by 2100; this analysis revealed that the heat-related deaths will increase more than the cold-related deaths avoided in the hot and wet months, and overall the net increase in expected mortality by region ranges from 5 to 13 % unless preventive measures were adopted. Overall, these results are useful for health impact assessment for the present situation and future public health implication of global climate change for tropical Thailand.     

The global impact of income inequality on health by age: an observational study

Objectives To explore whether the apparent impact of income inequality on health, which has been shown for wealthier nations, is replicated worldwide, and whether the impact varies by age.Design Observational study. Setting 126 countries of the world for which complete data on income inequality and mortality by age and sex were available around the year 2002 (including 94.4% of world human population).Data sources Data on mortality were from the World Health Organization and income data were taken from the annual reports of the United Nations Development Programme.Main outcome measures Mortality in 5-year age bands for each sex by income inequality and income level.Results At ages 15-29 and 25-39 variations in income inequality seem more closely correlated with mortality worldwide than do variations in material wealth. This relation is especially strong among the poorest countries in Africa. Mortality is higher for a given level of overall income in more unequal nations.Conclusions Income inequality seems to have an influence worldwide, especially for younger adults. Social inequality seems to have a universal negative impact on health.     

The origins of monetary income inequality: Patience,human capital,and division of labor

We present an explanation about the origins of monetary income inequality when an economically self-sufficient society opens to a market economy. The chain of associations runs from patience, to the accumulation of different forms of human capital, to self-selection into different occupations, and to the division of labor, which contributes to monetary income inequality. In a self-sufficient society, patience is exogenously determined and people rely on folk knowledge as the only form of human capital. With the establishment of schools, patient and impatient people sort themselves out by the type of human capital they begin to accumulate. Impatient people do not acquire folk knowledge because return to schooling takes many years to bear fruit. Schooling opens opportunities in occupations outside the village, whereas folk knowledge enhances employment opportunities that draw on farming or foraging. Self-selection into different occupations with different earnings potential spawns monetary income inequality. To test the explanation, we draw on data from a foraging–farming society in the Bolivian Amazon, the Tsimane'. We collected data during four consecutive quarters in 1999–2000 and a follow-up interview (2004). Data came from 151 adults (age, 16 years or more) from all households (n=48) in two villages with different levels of market exposure. During 1999–2000, impatience was associated with (a) greater folk knowledge and fewer years of schooling, (b) lower likelihood of working in wage labor, and (c) greater likelihood of working in rural subsistence occupations. People who had been patient in 1999–2000 had greater wage earnings and more modern physical assets in 2004.