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

Household income unequally affects genetic susceptibility to pulmonary diseases: evidence from bidirectional Mendelian randomization study

Objectives

Previous observational studies have reported a close association between socioeconomic status and pulmonary disease-related morbidity. However, the inherent causal effects remain unclear. Therefore, this bidirectional Mendelian randomization (MR) study aimed to identify the causal relationship between household income and genetic susceptibility to pulmonary diseases.

Methods

An MR study was conducted on a large cohort of European individuals, using publicly available genome-wide association study datasets using a random-effects inverse-variance weighting model as the main standard. Simultaneously, MR-Egger regression, weighted median, and maximum likelihood estimation were applied as supplements. Sensitivity analysis, comprising a heterogeneity test and horizontal pleiotropy test, was performed using the Cochran's Q, MR-Egger intercept, and MR-PRESSO tests to ensure the reliability of the conclusion.

Results

A higher household income tended to lower the risk of genetic susceptibility to chronic obstructive pulmonary disease (COPD, OR: 0.497, 95% CI = 0.337-0.733, p < 0.001), asthma (OR: 0.687, 95% CI = 0.540-0.876, p = 0.002), and lung cancer (OR: 0.569, 95% CI = 0.433-0.748, p < 0.001), and further indicated potential causality with pneumonia (OR: 0.817; 95% CI = 0.686-0.972, p = 0.022). No association was evident with COVID-19 (OR: 0.934, 95% CI = 0.764-1.142, p = 0.507), tuberculosis (OR: 0.597, 95% CI = 0.512-1.189, p = 0.120), or bronchiectasis (OR: 0.680, 95% CI = 0.311-1.489, p = 0.400). Reverse MR analysis suggested no reverse causal relationship between pulmonary disease and household income status, while sensitivity analysis verified the reliability of the results.

Conclusion

The results revealed that the population with a higher household income tended to have a lower risk of genetic susceptibility to COPD, asthma, and lung cancer.

Social determinants of respiratory health from birth: still of concern in the 21st century?

Respiratory symptoms are ubiquitous in children and, even though they may be the harbinger of poor long-term outcomes, are often trivialised. Adverse exposures pre-conception, antenatally and in early childhood have lifetime impacts on respiratory health. For the most part, lung function tracks from the pre-school years at least into late middle age, and airflow obstruction is associated not merely with poor respiratory outcomes but also early all-cause morbidity and mortality. Much would be preventable if social determinants of adverse outcomes were to be addressed. This review presents the perspectives of paediatricians from many different contexts, both high and low income, including Europe, the Americas, Australasia, India, Africa and China. It should be noted that there are islands of poverty within even the highest income settings and, conversely, opulent areas in even the most deprived countries. The heaviest burden of any adverse effects falls on those of the lowest socioeconomic status. Themes include passive exposure to tobacco smoke and indoor and outdoor pollution, across the entire developmental course, and lack of access even to simple affordable medications, let alone the new biologicals. Commonly, disease outcomes are worse in resource-poor areas. Both within and between countries there are avoidable gross disparities in outcomes. Climate change is also bearing down hardest on the poorest children. This review highlights the need for vigorous advocacy for children to improve lifelong health. It also highlights that there are ongoing culturally sensitive interventions to address social determinants of disease which are already benefiting children.

Thinness negatively affects lung function among Sri Lankan children

Background

There have been conflicting findings on the effect of body mass index (BMI) on lung functions in children. Therefore, we studied the relationship between spirometry parameters and BMI among healthy Sri Lankan school children aged 5–7 years.

Methods

A cross-sectional study was conducted among 296 school children (5–7-year-old) without apparent lung disease. Recruitment was done with stratified random sampling. Spirometry parameters, FEV₁, FVC, PEFR, and FEV₁/FVC ratio were determined. The acceptable and reproducible spirometry recordings were included in the analysis. Simple and multivariate linear regression analysis examined possible associations of lung function parameters with BMI, socio‐demographic variables and indoor risk factors. Also, the mediator effect of gender on lung function through BMI was explored.

Results

The participants’ mean age (SD) was 6.4 (0.65) years. One-third were thin/severely thin (37%). A statistically significant difference in FVC (p = 0.001) and FEV₁ (p = 0.001) was observed between BMI groups (obesity/overweight, normal, and thinness). Yet, PEFR or FEV₁/FVC did not significantly differ among BMI groups (p = 0.23 and p = 0.84). Multivariate regression analysis showed that FEV₁ and FVC were significantly associated with BMI, child’s age, gender, family income, father’s education, having a pet, and exposure to mosquito coil smoke. Interaction between gender and BMI for lung functions was not significant. The thin children had significantly lower FVC (OR: -0.04, 95%CI: -0.077, -0.012, p = 0.008) and FEV₁ (OR: -0.04, 95%CI: -0.075, -0.014, p = 0.004) than normal/overweight/obese children. Family income demonstrated the greatest effect on lung functions; FVC and FEV₁ were 0.25L and 0.23L smaller in low-income than the high-income families.

Conclusion

Lower lung function parameters (FVC and FEV₁) are associated with thinness than normal/overweight/obese dimensions among children without apparent lung disease. It informs that appropriate nutritional intervention may play a role in improving respiratory health.

Prognostic implications of differences in forced vital capacity in black and white US adults: Findings from NHANES III with long-term mortality follow-up

BACKGROUND

Because Forced Vital Capacity (FVC) is reduced in Black relative to White Americans of the same age, sex, and height, standard lung function prediction equations assign a lower "normal" range for Black patients. The prognostic implications of this race correction are uncertain.

METHODS

We analyzed 5,294 White and 3,743 Black participants age 20-80 in NHANES III, a nationally-representative US survey conducted 1988-94, which we linked to the National Death Index to assess mortality through December 31, 2015. We calculated the FVC-percent predicted among Black and White participants, first applying NHANES III White prediction equations to all persons, and then using standard race-specific prediction equations. We used Cox proportional hazard models to calculate the association between race and all-cause mortality without and with adjustment for FVC (using each FVC metric), smoking, socioeconomic factors, and comorbidities.

FINDINGS

Black participants' age- and sex-adjusted mortality was greater than White participants (HR 1.46; 95%CI:1.29, 1.65). With adjustment for FVC in liters (mean 3.7 L for Black participants, 4.3 L for White participants) or FVC percent-predicted using White equations for everyone, Black race was no longer independently predictive of higher mortality (HR∼1.0). When FVC-percent predicted was "corrected" for race, Black individuals again showed increased mortality hazard. Deaths attributed to chronic respiratory disease were infrequent for both Black and White individuals.

INTERPRETATION

Lower FVC in Black people is associated with elevated risk of all-cause mortality, challenging the standard assumption about race-based normal limits. Black-White disparities in FVC may reflect deleterious social/environmental exposures, not innate differences.

FUNDING

No funding.

Socioeconomic Inequality in Respiratory Health in the US From 1959 to 2018

Importance

Air quality has improved and smoking rates have declined over the past half-century in the US. It is unknown whether such secular improvements, and other policies, have helped close socioeconomic gaps in respiratory health.

Objective

To describe long-term trends in socioeconomic disparities in respiratory disease prevalence, pulmonary symptoms, and pulmonary function.

Design, Setting, and Participants

This repeated cross-sectional analysis of the nationally representative National Health and Nutrition Examination Surveys (NHANES) and predecessor surveys, conducted from 1959 to 2018. included 160 495 participants aged 6 to 74 years.

Exposures

Family income quintile defined using year-specific thresholds; educational attainment.

Main Outcomes and Measures

Trends in socioeconomic disparities in prevalence of current/former smoking among adults aged 25 to 74 years; 3 respiratory symptoms (dyspnea on exertion, cough, and wheezing) among adults aged 40 to 74 years; asthma stratified by age (6-11, 12-17, and 18-74 years); chronic obstructive pulmonary disease ([COPD] adults aged 40-74 years); and 3 measures of pulmonary function (forced expiratory volume in 1 second [FEV1], forced vital capacity [FVC], and FEV1/FVC<0.70) among adults aged 24 to 74 years.

Results

Our sample included 160 495 individuals surveyed between 1959 and 2018: 27 948 children aged 6 to 11 years; 26 956 children aged 12 to 17 years; and 105 591 adults aged 18 to 74 years. Income- and education-based disparities in smoking prevalence widened from 1971 to 2018. Socioeconomic disparities in respiratory symptoms persisted or worsened from 1959 to 2018. For instance, from 1971 to 1975, 44.5% of those in the lowest income quintile reported dyspnea on exertion vs 26.4% of those in the highest quintile, whereas from 2017 to 2018 the corresponding proportions were 48.3% and 27.9%. Disparities in cough and wheezing rose over time. Asthma prevalence rose for all children after 1980, but more sharply among poorer children. Income-based disparities in diagnosed COPD also widened over time, from 4.5 percentage points (age- and sex-adjusted) in 1971 to 11.3 percentage points from 2013 to 2018. Socioeconomic disparities in FEV1 and FVC also increased. For instance, from 1971 to 1975, the age- and height-adjusted FEV1 of men in the lowest income quintile was 203.6 mL lower than men in the highest quintile, a difference that widened to 248.5 mL from 2007 to 2012 (95% CI, -328.0 to -169.0). However, disparities in rates of FEV1/FVC lower than 0.70 changed little.

Conclusions and Relevance

Socioeconomic disparities in pulmonary health persisted and potentially worsened over the past 6 decades, suggesting that the benefits of improved air quality and smoking reductions have not been equally distributed. Socioeconomic position may function as an independent determinant of pulmonary health.

Longitudinal Association of Economic Growth with Lung Function of Chinese Children and Adolescents over 30 Years: Evidence from Seven Successive National Surveys

(1) Background: Recent studies reported that decrease in lung function of Chinese children and adolescents continues to decline, although the change has been insignificant and has reached a plateau. However, studies have not explored the relationship between lung function and economic development in China. This study sought to explore the longitudinal association between socio-economic indicators and lung function; (2) Method: Data were obtained from seven successive national surveys conducted by the Chinese National Survey on Students' Constitution and Health from 1985 to 2014. Lung function of school-age children (7-22 years) was determined using forced vital capacity (FVC). GDP per capita and urbanization ratio were used as economic indicators. A fixed-effects model was employed to examine the longitudinal association after adjusting for height, weight, and time trends; (3) Results: Socio-economic indicators showed a U-curve relationship with lung function of boys and girls from urban and rural areas. Lung function initially decreased with GDP per capita or urbanization ratio and reached a minimum. Lung function then increased with increase in GDP per capita or urbanization ratio. The findings indicate that the relationship between economic growth and lung function is different in different development stages. In less-developed provinces, economic growth was negatively correlated with lung function, whereas, in developed provinces, economic growth was positively correlated with lung function; (4) Conclusion: The findings of the current study show that economic growth has significantly different effects on lung function at different economic levels. Therefore, governments should improve lung health in children and adolescents from low and middle economic regions.

Life-course socioeconomic disadvantage and lung function: a multicohort study of 70 496 individuals

BACKGROUND

Lung function is an important predictor of health and a marker of physical functioning at older ages. This study aimed to quantify the years of lung function lost according to disadvantaged socioeconomic conditions across the life-course.

METHODS

This multicohort study used harmonised individual-level data from six European cohorts with information on life-course socioeconomic disadvantage and lung function assessed by forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC). 70 496 participants (51% female) aged 18-93 years were included. Socioeconomic disadvantage was measured in early life (low paternal occupational position), early adulthood (low educational level) and adulthood (low occupational position). Risk factors for poor lung function (e.g. smoking, obesity, sedentary behaviour, cardiovascular and respiratory diseases) were included as potential mediators. The years of lung function lost due to socioeconomic disadvantage were computed at each life stage.

RESULTS

Socioeconomic disadvantage during the life-course was associated with a lower FEV1. By the age of 45 years, individuals experiencing disadvantaged socioeconomic conditions had lost 4-5 years of healthy lung function versus their more advantaged counterparts (low educational level -4.36 (95% CI -7.33--2.37) for males and -5.14 (-10.32--2.71) for females; low occupational position -5.62 (-7.98--4.90) for males and -4.32 (-13.31--2.27) for females), after accounting for the risk factors for lung function. By the ages of 65 years and 85 years, the years of lung function lost due to socioeconomic disadvantage decreased by 2-4 years, depending on the socioeconomic indicator. Sensitivity analysis using FVC yielded similar results to those using FEV1.

CONCLUSION

Life-course socioeconomic disadvantage is associated with lower lung function and predicts a significant number of years of lung function loss in adulthood and at older ages.

Life-course socioeconomic status and lung function in adulthood: a study in the EPIPorto cohort

OBJECTIVE

This study aims to investigate the association of life-course socioeconomic status (SES) with lung function during adulthood, by exploring the influence of life-course social mobility and of cumulative exposure to low SES.

METHODS

Participants were 1458 individuals from EPIPorto study, a population-based cohort of Portuguese adults. The life-course SES was computed using participants' paternal occupation and own occupation, resulting in four patterns: stable high, upward, downward, stable low. A cumulative life-course SES index was also calculated using the participants' paternal occupation, own education and occupation. Lung function during adulthood was assessed with forced expiratory volume in first second (FEV₁) and forced vital capacity (FVC) percentages predicted (higher percentages are associated with better lung function). Linear regression models were used to estimate beta coefficients and 95% CI for the association of socioeconomic indicators and lung function.

RESULTS

Disadvantaged SES from childhood to adulthood was associated with lower lung function (FEV₁:-6.64%,-10.68;-2.60/FVC:-3.77%,-7.45;-0.08), and the greater the socioeconomic disadvantage, the lower the lung function (FEV₁:-2.56%,-3.98;-1.15/FVC:-1.54%,-2.83;-0.24) among men, independently of marital status and behavioural factors. Among women, SES effects were only observed in those experiencing a stable low life-course SES at older ages (-5.15%,-10.20;-0.09). Men experiencing a downward social mobility presented the lowest lung function, but there was attenuation to the null after accounting for marital status and behavioural factors.

CONCLUSION

A life-course disadvantaged SES is an important predictor of lower lung function during adulthood. Downward social mobility was associated with the lowest lung function among men, although this association was mostly explained by behavioural factors.

Socioeconomic circumstances and respiratory function from childhood to early adulthood: a systematic review and meta-analysis

OBJECTIVE

Disadvantaged socioeconomic circumstances in early life have the potential to impact lung function. Thus, this study aimed to summarise evidence on the association between socioeconomic circumstances and respiratory function from childhood to young adulthood.

DESIGN

Systematic review and meta-analysis.

METHODS

Following the Preferred Reporting Items for Systematic Review and Meta-analysis guidelines, Medline, ISI-Web of Science and Scopus were searched from inception up to January 2018. Original studies on the association between socioeconomic circumstances and respiratory function in early ages (ie, participants younger than 25 years of age) were investigated. Two investigators independently evaluated articles, applied the exclusion criteria, extracted data and assessed the risk of bias using the Newcastle-Ottawa Scale. A meta-analysis of the standardised mean difference and 95% CI in respiratory function between participants from different socioeconomic circumstances was conducted, using a random-effects model.

RESULTS

Thirty-three papers were included in this review and 23 showed that disadvantaged socioeconomic circumstances were significantly associated with reduced respiratory function. The meta-analysis including seven papers showed a significant difference of -0.31 (95% CI -0.42 to -0.21) litres in forced expiratory volume in the first second between children, adolescents and young adults from disadvantaged versus advantaged socioeconomic circumstances. Specifically a difference of -0.31 (95% CI -0.51 to -0.10) litres in girls and -0.43 (95% CI -0.51 to -0.35) litres in boys was observed.

CONCLUSIONS

Children, adolescents and young adults from disadvantaged socioeconomic circumstances had lower respiratory function, and boys presented higher respiratory health inequalities. This information contributes to explain the social patterning of respiratory diseases, and might enable health policy makers to tackle respiratory health inequalities at early ages.

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.

Disparities in pulmonary fibrosis care in the United States: an analysis from the Nationwide Inpatient Sample

Background

Idiopathic pulmonary fibrosis is a disease with high morbidity and mortality. Care for these patients, including lung transplantation, may provide significant benefits, but is resource-intensive and expensive. Disadvantaged patients with IPF may hence be at risk for receiving inferior care.

Methods

We analyzed data from the Nationwide Inpatient Sample, a database consisting of all hospitalizations from a 20% sample of US hospitals. We identified adults hospitalized with IPF between 1998 and 2011 using ICD-9 codes. We assessed the effect of insurance coverage and socioeconomic status (SES) on lung transplantation, a treatment that may improve survival. We also examined the effect of coverage and SES on mortality, as well as discharge to inpatient rehabilitation and receipt of a lung biopsy, two markers of the intensity of care delivered. We used multiple logistic regression to adjust for patient and hospital characteristics.

Results

We identified 148,877 hospitalizations that met our definition of pulmonary fibrosis. In the main adjusted analyses, hospitalizations of patients with Medicaid (OR 0.30, 95% CI 0.16–0.57) or no insurance (OR 0.22, 95% CI 0.07–0.72) were less likely to result in a lung transplantation compared to hospitalizations of those with non-Medicaid insurance. Those of lower SES were also less likely to undergo transplantation, while hospitalized patients with Medicaid and the uninsured were less likely to be discharged to inpatient rehabilitation or to receive a lung biopsy.

Conclusions

Among hospitalized patients with IPF, those with lower SES, Medicaid coverage and without insurance were less likely to receive several clinical interventions.

Electronic supplementary material

The online version of this article (10.1186/s12913-018-3407-0) contains supplementary material, which is available to authorized users.

Ethnic differences in spirometry measurements in China: Results from a large community-based epidemiological study

BACKGROUND AND OBJECTIVE

No previous studies have examined differences in spirometry measurements among ethnic populations in China, and factors which may influence ethnic differences are unclear. Our study aimed to investigate whether forced expiratory volume in 1 s (FEV₁ ) and forced vital capacity (FVC) differ among Han Chinese and other ethnic minorities in China.

METHODS

We recruited 7137 individuals aged 35-70 years from four areas of China inhabited by ethnic minority groups between 2007 and 2009. We conducted spirometry tests for all available participants, and compared FEV₁ and FVC among Uygur, Hui, Mongolian, Dai and Han Chinese ethnicities, using nonlinear multiplicative regression models.

RESULTS

A total of 2005 healthy never-smokers were enrolled in the analysis. For all ethnicities, spirometry values increased with height and decreased with age; FEV₁ and FVC were consistently higher in males than in females. Compared with Han Chinese, FEV₁ was 4.42% (95% CI: 2.11-6.78%) higher in Mongolians, 4.08% (95% CI: 1.33-6.76%) lower in Uygurs, 4.39% (95% CI: 1.33-7.35%) lower in Hui people and 4.72% (95% CI: 1.80-7.55%) lower in Dai people, after adjusted for potential confounders including height, age, sex and place of residence. We observed similar differences for FVC.

CONCLUSIONS

We detected significant differences in spirometry measurements among ethnic populations in China. Such differences cannot be fully explained by demographic, anthropometric or socioeconomic factors, but may also be attributed to genetic background as well as indoor and outdoor environmental exposures that need further investigation.

Impacts of low socioeconomic status and polycyclic aromatic hydrocarbons exposure on lung function among a community-based Chinese population

Lung function is related to socioeconomic status (SES) and exposure to polycyclic aromatic hydrocarbons (PAHs). However, joint effect of SES and exposure to PAHs on lung function has been largely unknown. We aimed to investigate joint effects of SES and urinary OH-PAHs levels on lung function parameters. This study included 2739 Wuhan participants from the baseline survey of the Wuhan-Zhuhai (WHZH) Cohort Study (n=3053). They completed the questionnaire, physical examination and provided blood and urine samples. Twelve urinary monohydroxy-PAHs metabolites (OH-PAHs) and lung function were measured by gas chromatography-mass spectrometry and digital spirometers, respectively. Individuals with low educational levels and low or high levels of urinary ΣOH-PAHs had a 3.5% (95% CI: -5.4, -1.6%) or 4.2% (95% CI: -6.1, -2.3%) reduction in the ratio of forced expiratory volume in 1s to forced vital capacity (FEV1/FVC), respectively, and those with middle levels of education and high levels of urinary ΣOH-PAHs had a 2.1% (95% CI: -5.4, -1.6%) reduction in the FEV1/FVC ratio, rather than those with high levels of education and low levels of urinary ΣOH-PAHs. Individuals with low levels of education had a -3.0% (95% CI: -4.4, -1.6%) reduction in FEV1/FVC compared with individuals with high levels of education. Urinary OH-PAHs levels were marginally negatively related to FEV1 in all participants (p=0.073). The results indicated that there was a prominent effect of low levels of education and higher exposure to PAHs on lung function decline, indicating that it is a necessary to take measures to promote the education level and reduce exposure to environmental PAHs.

Air Pollution and Children's Health in Chinese

Children can be considered as a high-risk population to environmental stress since some of the organ systems including the immune system and respiratory system are still in development during childhood. During childhood, the impact of environmental pollutants exposure may program child growth and development that have long-term consequences on later health and disease risk. Considering the rapid economic growth in recent decades in China, the impact of ambient air pollution on children health causes concerns. Therefore, we aimed to review the current epidemiological evidence on the effects of air pollution exposure on adverse health outcome, including respiratory diseases, lung function, high blood pressure, cognitive disorder, and obesity in childhood in China. We believe that the findings summarized in our review demonstrate an unequivocal relationship between air pollutants exposure and Chinese children health and these results have large public health influences.