How far can we explain the social class differential in respiratory function? A cross-sectional population study of 21,991 men and women from EPIC-Norfolk

The Role of Socioeconomic Status in the Association of Lung Function and Air Pollution-A Pooled Analysis of Three Adult ESCAPE Cohorts

Ambient air pollution is a leading environmental risk factor and its broad spectrum of adverse health effects includes a decrease in lung function. Socioeconomic status (SES) is known to be associated with both air pollution exposure and respiratory function. This study assesses the role of SES either as confounder or effect modifier of the association between ambient air pollution and lung function. Cross-sectional data from three European multicenter adult cohorts were pooled to assess factors associated with lung function, including annual means of home outdoor NO₂. Pre-bronchodilator lung function was measured according to the ATS-criteria. Multiple mixed linear models with random intercepts for study areas were used. Three different factors (education, occupation and neighborhood unemployment rate) were considered to represent SES. NO₂ exposure was negatively associated with lung function. Occupation and neighborhood unemployment rates were not associated with lung function. However, the inclusion of the SES-variable education improved the models and the air pollution-lung function associations got slightly stronger. NO₂ associations with lung function were not substantially modified by SES-variables. In this multicenter European study we could show that SES plays a role as a confounder in the association of ambient NO₂ exposure with lung function.

Socioeconomic status and pulmonary function, transition from childhood to adulthood: cross-sectional results from the polish part of the HAPIEE study

OBJECTIVE

Previous studies have reported inverse associations between socioeconomic status (SES) and lung function, but less is known about whether pulmonary function is affected by SES changes. We aimed to describe the relationship of changes of SES between childhood and adulthood with pulmonary function.

DESIGN

Cross-sectional study.

PARTICIPANTS

The study sample included 4104 men and women, aged 45-69 years, residents of Krakow, participating in the Polish part of the Health, Alcohol and Psychosocial Factors in Eastern Europe Project.

MAIN OUTCOME

Forced expiratory volume (FEV₁) and forced vital capacity (FVC) were assessed by the standardised spirometry procedure. Participants were classified into three categories of SES (low, moderate or high) based on information on parent's education, housing standard during childhood, own education, employment status, household amenities and financial status.

RESULTS

The adjusted difference in mean FVC between persons with low and high adulthood SES was 100 mL (p=0.005) in men and 100 mL (p<0.001) in women; the differences in mean FEV₁ were 103 mL (p<0.001) and 80 mL (p<0.001), respectively. Upward social mobility and moderate or high SES at both childhood and adulthood were related to significantly higher FEV₁ and FVC compared with low SES at both childhood and adulthood or downward social mobility.

CONCLUSIONS

Low SES over a life course was associated with the lowest lung function. Downward social mobility was associated with a poorer pulmonary function, while upward mobility or life course and moderate or high SES were associated with a better pulmonary function.

Gender Differences in the Association of Individual and Contextual Exposures with Lung Function in a Rural Canadian Population

INTRODUCTION

To investigate the association of individual and contextual exposures with lung function by gender in rural-dwelling Canadians.

METHODS

A cross-sectional mail survey obtained completed questionnaires on exposures from 8263 individuals; a sub-sample of 1609 individuals (762 men, 847 women) additionally participated in clinical lung function testing. The three dependent variables were forced expired volume in one second (FEV₁), forced vital capacity (FVC), and FEV₁/FVC ratio. Independent variables included smoking, waist circumference, body mass index, indoor household exposures (secondhand smoke, dampness, mold, musty odor), occupational exposures (grain dust, pesticides, livestock, farm residence), and socioeconomic status. The primary analysis was multiple linear regression, conducted separately for each outcome. The potential modifying influence of gender was tested in multivariable models using product terms between gender and each independent variable.

RESULTS

High-risk waist circumference was related to reduced FVC and FEV₁ for both genders, but the effect was more pronounced in men. Greater pack-years smoking was associated with lower lung function values. Exposure to household smoke was related to reduced FEV₁, and exposure to livestock, with increased FEV₁. Lower income adequacy was associated with reduced FVC and FEV₁.

CONCLUSION

High-risk waist circumference was more strongly associated with reduced lung function in men than women. Longitudinal research combined with rigorous exposure assessment is needed to clarify how sex and gender interact to impact lung function in rural populations.

Socioeconomic status is associated with reduced lung function in China: an analysis from a large cross-sectional study in Shanghai

BACKGROUND

An inverse association between socioeconomic status and pulmonary function has emerged in many studies. However, the mediating factors in this relationship are poorly understood, and might be expected to differ between countries. We sought to investigate the relationship between socioeconomic status and lung function in China, a rapidly industrializing nation with unique environmental challenges, and to identify potentially-modifiable environmental mediators.

METHODS

We used data from the Shanghai Putuo Study, a cross-sectional study performed in Shanghai, China. Participants completed a questionnaire and spirometry. The primary exposure was socioeconomic status, determined by education level. The primary outcomes were FEV1 and FVC percent predicted. Multiple linear regressions were used to test this association, and the percent explained by behavioral, environmental, occupational, and dietary variables was determined by adding these variables to a base model.

RESULTS

The study population consisted of a total of 22,878 study subjects that were 53.3 % female and had a mean age of 48. In the final multivariate analysis, the effect estimates for FEV1 and FVC percent predicted for low socioeconomic status (compared to high) were statistically significant at a p-value of <0.01. Smoking, biomass exposure, mode of transportation to work, a diet low in fruits or vegetables, and occupational category partially attenuated the relationship between SES and lung function. In a fully-adjusted age-stratified analysis, the socioeconomic disparity in lung function widened with increasing age.

CONCLUSIONS

We found cross-sectional evidence of socioeconomic disparities in pulmonary function in Shanghai. These differences increased with age and were partially explained by potentially modifiable exposures.

MUC5AC and inflammatory mediators associated with respiratory outcomes in the British 1946 birth cohort

Background and objective: Dysregulation of respiratory mucins, MUC5AC in particular, has been implicated in respiratory disease and MUC5AC expression is up-regulated in response to environmental challenges and inflammatory mediators. The aim of this study was to examine the effect of genetic variation on susceptibility to common respiratory conditions.

Methods: The association of MUC5AC and the closely linked genes MUC2 and MUC5B with respiratory outcomes was tested in the MRC National Survey of Health and Development, a longitudinal birth cohort of men and women born in 1946. Also examined were the functional variants of the genes encoding inflammatory mediators, IL13, IL1B, IL1RN, TNFA and ERBB1, for which there is a likely influence on MUC5AC expression and were explored potential gene-gene interactions with these inflammatory mediators.

Results: Statistically significant associations between the 3'ter MUC5AC simple nucleotide polymorphism (SNP) rs1132440 and various non-independent respiratory outcomes (bronchitis, wheeze, asthma, hay fever) were reported while the adjacent loci show slight (but largely non-statistically significant) differences, presumably reflective of linkage disequilibrium (allelic association) across the region. A novel association between bronchitis and a non-synonymous functional ERBB1 SNP, rs2227983 (aka epidermal growth factor receptor:R497K, R521K) is also reported and evidence presented of interaction between MUC5AC and ERBB1 and between MUC5AC and IL1RN with respect to bronchitis. The ERBB1 result suggests a clear mechanism for a biological interaction in which the allelic variants of epidermal growth factor receptor differentially affect mucin expression.

Conclusions: The MUC5AC association and the interactions with inflammatory mediators suggest that genetically determined differences in MUC5AC expression alter susceptibility to respiratory disease.

SUMMARY AT A GLANCE

This longitudinal cohort study shows occurrence of the common respiratory conditions bronchitis, wheeze, asthma and hay fever to be associated with genetic variation in a mucin gene, MUC5AC. Functional variation in the epidermal growth factor receptor (epidermal growth factor receptor encoded by ERBB1) is also associated with bronchitis and modulates the MUC5AC effect.

Explaining the social patterning of lung function in adulthood at different ages: the roles of childhood precursors, health behaviours and environmental factors

Background

Lung function successfully predicts subsequent health. Although lung function is known to decline over age, little is known about changes in association with socioeconomic status (SES) throughout life, and whether explanatory factors for association vary with age or patterns for non smokers.

Methods

Analyses were based on data on 24 500 participants aged ≥18 years from the 1995, 1998 and 2003 Scottish Health Surveys who were invited to provide 1 s forced expiratory volume (FEV₁) and forced vital capacity (FVC) lung measurements. Sex-stratified multiple linear regression assessed lung function–SES (occupational social class) associations and attenuation by covariates in three age groups (2003 data (n=7928)).

Results

The FEV₁–SES patterns were clear (p<0.001) and constant over time. Relative to the least disadvantaged, FEV₁ in the most disadvantaged was lower by 0.28 L in men and 0.20 L in women under 40 years compared with differences of 0.51 L in men and 0.25 L in women over 64 years (p_interaction<0.001 men, p_interaction=0.004 women). The greatest attenuation of these results was seen by height, parental social class and smoking, especially among the under 65s. Second-hand smoke exposure and urban/rural residence had some impact among older groups. Adjusting for physical activity and weight had little effect generally. Similar patterns were seen for FVC and among never smokers.

Conclusions

We found cross-sectional evidence that SES disparity in lung function increases with age, especially for men. Our findings indicate that early-life factors may predict inequity during younger adulthood, with environmental factors becoming more important at older ages.

Demographic and disease-related predictors of abnormal lung function in patients with established inflammatory polyarthritis and a comparison with the general population

Objectives

To identify demographic and clinical predictors of obstructive lung disease (OLD) and restrictive lung disease (RLD) in patients with established inflammatory polyarthritis (IP) and to compare the prevalence of respiratory symptoms in patients with IP and the general population.

Method

A total of 421 patients with IP underwent a spirometry test 15 years after inclusion in the Norfolk Arthritis Register (NOAR). Logistic regression analyses were performed to assess the predictive ability of demographic and clinical characteristics obtained at inclusion in NOAR and to assess their association with OLD or RLD at 15 years (age- and gender-adjusted). In addition, the prevalence of OLD and RLD was compared with a matched population (1:4) of people participating in the European Prospective Investigation of Cancer-Norfolk, a representative sample of the general population in Norfolk, UK.

Results

In this IP population, current smoking was the strongest predictor for OLD and functional disability for RLD. In the comparison study, 11.6% had OLD in the IP population and 4.9% in the general population (adjOR 2.01, 95% CI 1.26 to 3.22). The prevalence of RLD was not statistically different between the IP population and the general population (14.6% vs 17.5%; adjOR 0.76, 95% CI 0.53 to 1.10).

Conclusions

OLD, but not RLD, is more prevalent in the IP population than in the general population. Functional disability is especially associated with RLD whereas smoking is associated with OLD. The latter finding, and the known association between smoking and a poor disease prognosis, underlines the importance of smoking cessation in patients with IP.

Social gradients in oral health in older adults: findings from the English longitudinal survey of aging

OBJECTIVES

We examined prospective associations between socioeconomic position (SEP) markers and oral health outcomes in a national sample of older adults in England.

METHODS

Data were from the English Longitudinal Survey of Aging, a national cohort study of community-dwelling people aged 50 years and older. SEP markers (education, occupation, household income, household wealth, subjective social status, and childhood SEP) and sociodemographic confounders (age, gender, and marital status) were from wave 1. We collected 3 self-reported oral health outcomes at wave 3: having natural teeth (dentate vs edentate), self-rated oral health, and oral impacts on daily life. Using multivariate logistic regression models, we estimated associations between each SEP indicator and each oral health outcome, adjusted for confounders.

RESULTS

Irrespective of SEP marker, there were inverse graded associations between SEP and edentulousness, with proportionately more edentate participants at each lower SEP level. Lower SEP was also associated with worse self-rated oral health and oral impacts among dentate, but not among edentate, participants.

CONCLUSIONS

There are consistent and clear social gradients in the oral health of older adults in England, with disparities evident throughout the SEP hierarchy.

The Rotterdam Study: 2012 objectives and design update

The Rotterdam Study is a prospective cohort study ongoing since 1990 in the city of Rotterdam in The Netherlands. The study targets cardiovascular, endocrine, hepatic, neurological, ophthalmic, psychiatric, dermatological, oncological, and respiratory diseases. As of 2008, 14,926 subjects aged 45 years or over comprise the Rotterdam Study cohort. The findings of the Rotterdam Study have been presented in over a 1,000 research articles and reports (see www.erasmus-epidemiology.nl/rotterdamstudy ). This article gives the rationale of the study and its design. It also presents a summary of the major findings and an update of the objectives and methods.

Socioeconomic trajectory from birth to adolescence and lung function: prospective birth cohort study

Background

Socioeconomic status (SES) has been shown to be an important contributor to lung function. The aim of this study was to evaluate the association between lung function in adolescence and (a) SES at birth; (b) SES in adolescence; (c) SES trajectory from birth to adolescence ('never poor', 'non poor-poor', 'poor-non poor' and 'always poor'). Additionally, we investigate the role of adolescent and parental variables at mediating these associations.

Methods

Prospective birth cohort study in Pelotas, Brazil, including 4,005 adolescents (mean age: 14.7 years) followed up from birth. Lung function was measured by spirometry. Outcome variables were forced expiratory volume in one second in liters (FEV1) and forced vital capacity also in liters (FVC).

Results

Mean FEV1 was 3.46 L (95%CI 3.43-3.49) among boys and 2.93 L (95%CI 2.91-2.95) among girls. Mean FVC was 4.00 L (95%CI 3.97; 4.04) among boys and 3.30 L (95%CI 3.27; 3.32) among girls. SES at birth, in adolescence and its trajectory from birth to adolescence were inversely associated with lung function in both adolescent boys and girls. After adjustment for mediating variables, coefficients were largely reduced, particularly among boys, and the main predictor of change in coefficients was the inclusion of height in the models.

Conclusion

Low income adolescents from Brazil present impaired lung function as compared to the better off, and this is largely explained by height.

The Shanghai Changfeng Study: a community-based prospective cohort study of chronic diseases among middle-aged and elderly: objectives and design

The Shanghai Changfeng Study is a community-based prospective cohort study of chronic diseases ongoing since February 2009 in Shanghai, China. The study focuses on multiple chronic diseases, including obesity and metabolic syndrome, diabetes, osteoporosis, liver diseases, cardiovascular diseases and neurologic diseases. 15,000 subjects of 40 years or over are planned to be recruited. The rationale, objectives and design of this study are described in this paper.

The Generation R Study: design and cohort update 2010

The Generation R Study is a population-based prospective cohort study from fetal life until young adulthood. The study is designed to identify early environmental and genetic causes of normal and abnormal growth, development and health during fetal life, childhood and adulthood. The study focuses on four primary areas of research: (1) growth and physical development; (2) behavioural and cognitive development; (3) diseases in childhood; and (4) health and healthcare for pregnant women and children. In total, 9,778 mothers with a delivery date from April 2002 until January 2006 were enrolled in the study. General follow-up rates until the age of 4 years exceed 75%. Data collection in mothers, fathers and preschool children included questionnaires, detailed physical and ultrasound examinations, behavioural observations, and biological samples. A genome wide association screen is available in the participating children. Regular detailed hands on assessment are performed from the age of 5 years onwards. Eventually, results forthcoming from the Generation R Study have to contribute to the development of strategies for optimizing health and healthcare for pregnant women and children.