Does survey non-response bias the association between occupational social class and health?

AIMS: A non-response rate of 20-40%is typical in questionnaire studies. The authors evaluate non-response bias and its impact on analyses of social class inequalities in health. METHODS: Set in the context of a health survey carried out among the employees of the City of Helsinki (non-response 33%) in 2000-02. Survey response and non-response records were linked with a personnel register to provide information on occupational social class and long sickness absence spells as an indicator of health status. RESULTS: Women and employees in higher occupational social classes were more likely to respond. Non-respondents had about 20-30% higher sickness absence rates. Relative social class differences in sickness absence in the total population were similar to those among either respondents or non-respondents. CONCLUSIONS: In working populations survey non-response does not seriously bias analyses of social class inequalities in sickness absence and possibly health inequalities more generally.     

Does sleep quality mediate the association between neighborhood disorder and self-rated physical health?

ObjectivesWe examine the association between perceived neighborhood disorder and self-rated physical health. Building on previous research, we test whether this association is mediated by sleep quality.MethodsWe use data from the 2004 Survey of Texas Adults (n = 1323) to estimate a series of ordinary least squares regression models. We formally assess mediation by testing for significant changes in the effect of neighborhood disorder before and after adjusting for sleep quality.ResultsWe find that residence in a neighborhood that is perceived as noisy, unclean, and crime-ridden is associated with poorer self-rated physical health, even with controls for irregular exercise, poor diet quality, smoking, binge drinking, obesity and a host of relevant sociodemographic factors. Our results also indicate that the relationship between neighborhood disorder and self-rated physical health is partially mediated by lower sleep quality.ConclusionTargeted interventions designed to promote sleep quality in disadvantaged neighborhoods may help to improve the physical health of residents in the short-term. Policies aimed at solving the problem of neighborhood disorder are needed to support sleep quality and physical health in the long-term.     

Does the association between smoking and mortality differ by educational level?

Some researchers suggest that the effect of smoking on health depends on socioeconomic status; while others purport that the effect of smoking on health is similar across all social groups. This question of the interaction between smoking and socioeconomic status is important to an improved understanding of the role of smoking in the social gradient in mortality and morbidity. For this purpose, we examined whether educational level modifies the association between smoking and mortality. Information on smoking by age, gender and educational level was extracted from the Belgian Health Interview Surveys of 1997 and 2001. The mortality follow up of the survey respondents was reported until December 2010. A Poisson regression was used to estimate the hazard ratio of mortality for heavy smokers, light smokers, and former smokers compared with never smokers by educational level controlling for age and other confounders. Among men, we found lower hazard ratios in the lowest educational category compared with the intermediate and high-educated categories. For instance, for heavy smokers, the hazard ratios were 2.59 (1.18-5.70) for those with low levels of education, 4.03 (2.59-6.26) for those with intermediate levels of education and 3.78 (1.52-9.43) for the highly educated. However, the interaction between smoking and education was not statistically significant. For women, the hazard ratios were not significant for any educational category except for heavy smokers with intermediate levels of education. Also here the interaction was not statistically significant. Our results support the hypothesis that educational attainment does not substantially influence the association between smoking and mortality.     

Does the predictive power of self-rated health for subsequent mortality risk vary by socioeconomic status in the US?

BACKGROUND: The purpose of this study is to test whether the predictive power of an individual's self-rated health (SRH) on subsequent mortality risk differs by socioeconomic status (SES) in the United States. METHODS: We use the National Health Interview Survey 1986-94 linked to Multiple Cause of Death Files 1986-97 (NHIS-MCD). Analyses are based on non-Hispanic Black and White adults 25 and older (n = 358,388). Cox proportional hazard models are used to estimate the effect of SRH on mortality risk during follow-up. Interactions of SRH and level of education and SRH and level of income are used to assess differences in the predictive power of SRH for subsequent mortality risk. RESULTS: The effect of SRH on subsequent mortality risk differs by level of education and level of income. Lower health ratings are more strongly associated with mortality for adults with higher education and/or higher income relative to their lower SES counterparts. CONCLUSIONS: Our findings suggest that individuals with different education or income levels may evaluate their health differently with respect to the traditional five-point SRH scale, and hence their subjective health ratings may not be directly comparable. These results have important implications for research that tries to quantify and explain socioeconomic inequalities in health based on self-rated health.     

Do age and social relations moderate the relationship between self-rated health and mortality among adult Danes?

It is well established that self-rated health (SRH) predicts mortality even after controlling for a wide range of factors. We explored the extent to which age and social relations (structural and functional) influenced the relationship between SRH and mortality (after 13 years follow-up) in a representative sample of adult Danes (N=6693). After controlling for socioeconomic status, illness, and lifestyle variables, we found that age moderated the SRH-mortality relationship such that it was present for respondents under 55 but absent for respondents over 56. In addition, weaker structural (but not functional) social relations increased mortality directly but neither structural nor functional social relations moderated the SRH-mortality relationship. We discuss the theoretical and practical implications of these findings.     

Does social selection explain the association between state-level racial animus and racial disparities in self-rated health in the United States?

PurposeRacism, whether defined at individual, interpersonal, or structural levels, is associated with poor health among Blacks. This association may arise because exposure to racism causes poor health, but geographic mobility patterns pose an alternative explanation—namely, Black individuals with better health and resources can move away from racist environments.MethodsWe examine the evidence for selection effects using nationally representative, longitudinal data (1990–2009) from the Panel Study on Income Dynamics (n = 33,852). We conceptualized state-level racial animus as an ecologic measure of racism and operationalized it as the percent of racially-charged Google search terms in each state.ResultsAmong those who move out of state, Blacks reporting good self-rated health (SRH) are more likely to move to a state with less racial animus than Blacks reporting poor SRH (P = .01), providing evidence for at least some selection into environments with less racial animus. However, among Blacks who moved states, over 80% moved to a state within the same quartile of racial animus, and fewer than 5% resided in states with the lowest level of racial animus.ConclusionsGeographic mobility patterns are therefore likely to explain only a small part of the relationship between racial animus and SRH. These results require replication with alternative measures of racist attitudes and health outcomes.     

Do health behaviors mediate the association between social capital and health?

INTRODUCTION: There is increasing evidence that social capital is important for people's health. However, there is still considerable disagreement about the specific pathways that links social capital to health. This study investigates the hypothesis that the association between social capital and health is mediated by people's health behaviors. METHOD: Data from the 2002 Health Survey for England (n = 7394) were used and analyzed from a multilevel perspective. The association between social capital and self-rated health were examined before and after controlling for smoking, alcohol intake, and fruit/vegetable consumption. RESULTS: Social capital was found to be associated with self-rated health, as well as with the different health behaviors. In addition, the health behaviors were significantly related to self-rated health. However, controlling for smoking, alcohol intake, and fruit/vegetable consumption did not substantially affect the association between social capital and self-rated health. CONCLUSIONS: The results demonstrate that social capital and support are important determinants of self-rated health and health behaviors. But only limited support was found for the hypothesis that health behaviors mediate the association between social capital and health.     

The association between network social capital and self-rated health: Pouring old wine in new bottles?

This study examines whether there is an association between network social capital and self-rated health after controlling for social support. Moreover, we distinguish between network social capital that emerges from strong ties and weak ties. We used a cross-sectional representative sample of 815 adults from the Belgian population. Social capital is measured with the position generator and perceived social support with the MOS Social Support-scale. Results suggest that network social capital is associated with self-rated health after adjustment for social support. Because different social classes have access to different sets of resources, resources of friends and family from the intermediate and higher service classes are beneficial for self-rated health, whereas resources of friends and family from the working class appear to be rather detrimental for self-rated health. From a health-promoting perspective, these findings indicate that policy makers should deal with the root causes of socioeconomic disadvantages in society.     

The association between hardship and self-rated health: does the choice of indicator matter?

Purpose

The purpose of this study was to investigate the association between four specific forms of hardship (difficulty paying bills, ongoing financial stress, medication reduction due to cost, and food insecurity) and self-rated health among older men and women.

Does income inequality modify the association between air pollution and health?

BACKGROUND: It has been hypothesized that socioeconomic status may act as an effect modifier of the association between air pollution and health. In this study, we investigated whether income inequality may modify the association between fine particulate pollution and self-reported health. METHODS: We combined several different sources of data. Demographic and socio-economic data, at the individual level, were drawn from the 2001 US Behavioral Risk Factor Surveillance System (BRFSS). County-level particulate pollution data for the year 2001 were provided by the US Environmental Protection Agency. State-level income inequality was measured by the Gini index using US census data from the year 2000. We used a hierarchical logistic regression to model the association between general self-reported health and fine particulate pollution accounting for income inequality as an effect modifier and controlling for the usual confounders. RESULTS: We found that when income inequality is low (10th percentile of the Gini distribution), the odds of reporting fair or poor health for a 10microg/m3 increase in particulate pollution is 1.34 (95% confidence interval 1.21-1.48). The analogous odds ratio for higher income inequality (60th percentile of the Gini distribution) is 1.11 (95% confidence interval 1.06-1.16). CONCLUSIONS: Income inequality was found to be an effect modifier of the association between general self-reported health and particulate pollution. However, these findings challenged our hypothesis that people living in higher income inequality areas are more vulnerable to the impact of air pollution. We discuss the factors driving these results.     

Does social cohesion modify the association between area income deprivation and mental health? A multilevel analysis

BACKGROUND: Despite the increasing belief that the places where people live influence their health, there is surprisingly little consistent evidence for their associations with mental health. We investigated the joint effect of community and individual-level socio-economic deprivation and social cohesion on individual mental health status. METHODS: Multilevel analysis of population survey data on 10,653 adults aged 18-74 years nested within the 325 census enumeration districts in Caerphilly county borough, Wales, UK. The outcome measure was the Mental Health Inventory (MHI-5) subscale of the SF-36 instrument. A social cohesion subscale was derived from a factor analysis of responses to the Neighbourhood Cohesion scale and was modelled at individual and area level. Area income deprivation was measured by the percentage of low income households. RESULTS: Poor mental health was significantly associated with area-level income deprivation and low social cohesion after adjusting for individual risk factors. High social cohesion significantly modified the association between income deprivation and mental health: the difference between the predicted mean area mental health scores at the 10th and 90th centiles of the low income distribution was 3.7 in the low cohesion group and 0.9 in the high cohesion group (difference of the difference in means = 2.8, 95% CI: 0.2, 5.4). CONCLUSIONS: Income deprivation and social cohesion measured at community level are potentially important joint determinants of mental health. Further research on the impact of the social environment on mental health should investigate causal pathways in a longitudinal study.     

Does liver damage explain the inverse association between vitamin D status and mortality?

PurposeSeveral observational studies have linked vitamin D deficiency with an increased risk of all-cause mortality. Vitamin D deficiency is common among patients with liver diseases. In a random sample of the general population, we investigated whether the inverse association between vitamin D status and all-cause mortality could be explained by liver damage as reflected by increased levels of liver enzymes.MethodsWe included a total of 2649 persons examined in 1993–1994. Vitamin D status was assessed as serum 25-hydroxyvitamin D and liver enzyme levels were measured. Information on all-cause mortality was obtained from the Danish Central Personal Register until July 2011. Median follow-up time was 17.0 years, and there were 736 deaths.ResultsMultivariable Cox regression analyses with age as underlying time axis and delayed entry showed lower mortality risk with higher vitamin D levels and this was essentially unaffected by adjustment for liver enzyme levels with hazard ratio, 0.96 (95% confidence interval, 0.93–0.99) for a 10 nmol/L higher vitamin D level.ConclusionsThe present study did not support our hypothesis that the well-known association between low vitamin D status and mortality is explained by liver damage as reflected by levels of liver enzymes.     

Dichotomous or categorical response? Analysing self-rated health and lifetime social class

BACKGROUND: Self-rated health is a commonly used measure of health status, usually having three to five categories. The measure is often collapsed into a dichotomous variable of good versus less than good health. This categorization has not yet been justified. METHODS: Using data from the 1958 British birth cohort, we examined the relationship between socioeconomic conditions, indicated by occupational class at four ages, and self-rated health. Results obtained for a dichotomous variable using logistic regression were compared with alternative methods for ordered categorical variables including polytomous regression, cumulative odds, continuation ratio and adjacent categories models. RESULTS AND CONCLUSIONS: Findings concerning the relationship between socioeconomic position and self-rated health yielded by a logistic regression model were confirmed by alternative statistical methods which incorporate the ordered nature of self-rated health. Similarity of results was found regarding size and significance of main effects, type of association and interactive effects.     

Does high income buffer the association between adverse working conditions and ill health?

AIM: A study was undertaken to analyse the possible interaction between work environment and income for the probability of self-rated health being less than good. METHODS: Data from the Swedish Survey of Living Conditions for the years 1998 and 1999 were analysed. Employed 20- to 64-year-olds with a registered wage were included (n=5982). The synergy index (SI) was applied, using odds ratios from logistic regressions for men, women, and all. Low and high levels of physical demands, decision authority, skill discretion and psychological demands were separately combined with low- and high-wage income (median split). Full-time work and four sociodemographic factors were controlled for. RESULTS: Significant synergy was found for women when they were exposed to low income and a low level of skill discretion (SI=1.46 [1.01-2.13]), although this was attenuated by education level (SI=1.47 [0.96-2.25]). In general (both sexes), poor health caused by low income and unfavourable work is additive rather than multiplicatively exaggerating the risk among the jointly exposed. CONCLUSION: Work exposures in the form of high physical load, low levels of decision authority and skill discretion, or a high level of psychological demands were significantly related to poor health also when income was high, suggesting that high income does not seem to buffer the detrimental effects of adverse working conditions. As nearly half of employed women were found to be in circumstances marked by synergy, it seems a relevant public health issue to improve these women's conditions at work, by simultaneously increasing, for example, job variety and wages.     

Does socioeconomic status affect the association of social relationships and health? A moderator analysis

Background  

Social relations have repeatedly been found to be an important determinant of health. However, it is unclear whether the association between social relations and health is consistent throughout different status groups. It is likely that health effects of social relations vary in different status groups, as stated in the hypothesis of differential vulnerability. In this analysis we explore whether socioeconomic status (SES) moderates the association between social relations and health.     

Exercise participation and self-rated health: Do common genes explain the association?

The purpose of this study is to investigate whether there is an association between exercise participation and self-rated health and whether this association can be explained by common genes and/or common environmental influences. In a sample of 5,140 Dutch adult twins and their non-twin siblings from 2,831 families, exercise participation (sedentaries, light or moderate, vigorous exercisers) and self-rated health were assessed by survey. To investigate the etiology of the association, bivariate genetic models using structural equation modeling were applied to the data. The correlation between exercise participation and self-rated health is significant but modest (r = 0.20). Exercise participation and self-rated health are both heritable (around 50% of the variance of both phenotypes is explained by genetic factors). The genetic factors influencing exercise participation and self-rated health partially overlap (r = 0.36) and this overlap fully explains their phenotypic correlation. We conclude that the association between exercise and self-rated health can be explained by genes predisposing to both exercise participation and self-rated health. These genes may directly influence both phenotypes (pleiotropy). Alternatively, genes that affect exercise or self-rated health may indirectly influence the other phenotype through a causal relationship. We propose that identification of the genes that cause differences in␣exercise behavior will help resolve the issue of causality.     

Does social participation improve self-rated health in the older population? A quasi-experimental intervention study

Social participation has been linked to healthy aging and the maintenance of functional independence in older individuals. However, causality remains tenuous because of the strong possibility of reverse causation (healthy individuals selectively participate in social activities). We describe a quasi-experimental intervention in one municipality of Japan designed to boost social participation as a way of preventing long-term disability in senior citizens through the creation of ‘salons’ (or community centers). In this quasi-experimental intervention study, we compared 158 participants with 1391 non-participants in salon programs, and examined the effect of participation in the salon programs on self-rated health. We conducted surveys of community residents both before (in 2006) and after (in 2008) the opening of the salons. Even with a pre/post survey design, our study could be subject to reverse causation and confounding bias. We therefore utilized an instrumental variable estimation strategy, using the inverse of the distance between each resident's dwelling and the nearest salon as the instrument. After controlling for self-rated health, age, sex, equivalized income in 2006, and reverse causation, we observed significant correlations between participation in the salon programs and self-rated health in 2008. Our analyses suggest that participation in the newly-opened community salon was associated with a significant improvement in self-rated health over time. The odds ratio of participation in the salon programs for reporting excellent or good self-rated health in 2008 was 2.52 (95% CI 2.27–2.79). Our study provides novel empirical support for the notion that investing in community infrastructure to boost the social participation of communities may help promote healthy aging.