Socioeconomic Status and Longitudinal Lung Function of Healthy Mexican Children

Association Between Lung Function of Children and Their Socioeconomic Conditions: A Systematic Review

Objective

This study aims to evaluate the association between socioeconomic conditions and the lung function of children below 18 years old.

Design

Systematic review.

Methods

PRISMA guidelines were followed to browse relevant studies from 2013 to 2023. Data from the included studies were extracted after the Newcastle-Ottawa risk of bias tool was applied.

Main Outcome

Forced expiratory volume in the first second (FEV1) liters.

Results

20 papers with 89,619 participants were included. Logistic regression model for FEV1 based on multiple SES indices, suggested a positive association between lower respiratory function and a lower SES, with an interquartile odds ratio (OR) of 1.67 (95% CI 1.03-1.34).

Conclusion

Children from a lower socioeconomic status (SES) do exhibit lower lung function and addressing the causes of this can contribute to developing preventive public health strategies.

Limitations

Lack of appropriate reference values and varied indicators of socioeconomic status in the studies contributed to significant statistical differences.

Prospero Registration Number

CRD 42020197658.

Lung function and cognitive ability in children: a UK birth cohort study

BACKGROUND

Decreased adult lung function is associated with subsequent impairment in cognition. A similar relationship in early life could be of great policy importance, since childhood cognitive ability determines key adult outcomes, including socioeconomic status and mortality. We aimed to expand the very limited data available on this relationship in children, and hypothesised that reduced lung function would be longitudinally associated with decreased cognitive ability.

METHODS

Lung function was measured at age 8 (forced expiratory volume in one second (FEV₁), forced vital capacity (FVC); % predicted), and cognitive ability was measured at ages 8 (Wechsler Intelligence Scale for Children, third edition) and 15 (Wechsler Abbreviated Scale of Intelligence), in the Avon Longitudinal Study of Parents and Children. Potential confounders were identified as preterm birth, birth weight, breastfeeding duration, prenatal maternal smoking, childhood environmental tobacco smoke exposure, socioeconomic status and prenatal/childhood air pollution exposure. Univariable and multivariable linear models (n range=2332-6672) were fitted to assess the cross-sectional and longitudinal associations of lung function with cognitive ability, and change in cognitive ability between ages 8 and 15.

RESULTS

In univariate analyses, both FEV₁ and FVC at age 8 were associated with cognitive ability at both ages, but after adjustment, only FVC was associated with full-scale IQ (FSIQ) at ages 8 (β=0.09 (95% CI 0.05 to 0.12; p<0.001)) and 15 (β=0.06 (0.03 to 0.10; p=0.001)). We did not find evidence of an association between either lung function parameter and interval change in standardised FSIQ.

DISCUSSION

Reduced FVC, but not FEV₁, is independently associated with decreased cognitive ability in children. This low-magnitude association attenuates between ages 8 and 15, while no association is evident with longitudinal change in cognitive ability. Our results support a link between FVC and cognition across the life course, possibly due to shared genetic or environmental risk, rather than causation.

Socioeconomic circumstances and lung function growth from early adolescence to early adulthood

BACKGROUND

A reduced lung function in early adulthood is associated with respiratory and non-respiratory diseases and is a long-term predictor of mortality. This study investigated the association between early socioeconomic circumstances (SEC) and lung function growth trajectories from early adolescence until early adulthood.

METHODS

We analysed data from the EPITeen population-based study, including adolescents born in 1990. Study waves occurred at 13, 17 and 21 years of age. Information on sociodemographic, behavioural and health factors, anthropometry and spirometry was collected. Early-life SEC were assessed using maternal education and paternal occupational position. The forced expiratory volume in the first second (FEV₁) growth trajectories were drawn considering sex-and-height interactions over an 8-year period. Our sample included 2022 participants with complete information for the relevant variables.

RESULTS

Participants from most disadvantaged SEC presented lower FEV₁ at early adolescence compared to high-SEC counterparts, but differences seem to diminish with height growth. The effect of paternal occupational position in lung function growth trajectories was moderated by height, thus individuals from fathers with less advantaged occupational position had lower FEV₁ at early adolescence, but they had a faster FEV₁ growth over time.

CONCLUSIONS

Individuals from most disadvantaged SEC presented lower lung function at early adolescence compared to high-SEC counterparts; nevertheless, a catch-up growth was observed.

IMPACT

Lower socioeconomic circumstances were previously associated with reduced lung function and a higher risk of respiratory diseases in adults. Fewer studies analysed the effects of early-life socioeconomic circumstances in lung function growth during adolescence. Disadvantaged socioeconomic circumstances were associated with lower lung function in early adolescence. However, social differences diminished over adolescence, suggesting a catch-up growth of lung function among those from lower socioeconomic circumstances. An improved understanding of the mechanism underlying lung function catch-up (or the absence of catch-up) might support interventions to narrow social inequalities in respiratory health and should be further investigated.

Reference values for spirometry in Brazilian children

Objective:

To generate reference values for spirometry in Brazilian children 3-12 years of age and to compare those values with the values employed in the equations currently in use in Brazil.

Methods:

This study involved healthy children, 3-12 years of age, recruited from 14 centers (primary data) and spirometry results from children with the same characteristics in six databases (secondary data). Reference equations by quantile regressions were generated after log transformation of the spirometric and anthropometric data. Skin color was classified as self-reported by the participants. To determine the suitability of the results obtained, they were compared with those predicted by the equations currently in use in Brazil.

Results:

We included 1,990 individuals from a total of 21 primary and secondary data sources. Of those, 1,059 (53%) were female. Equations for FEV₁, FVC, the FEV₁/FVC ratio, FEF between 25% and 75% of the FVC (FEF_25-75%) and the FEF_25-75%/FVC ratio were generated for white-, black-, and brown-skinned children. The logarithms for height and age, together with skin color, were the best predictors of FEV₁ and FVC. The reference values obtained were significantly higher than those employed in the equations currently in use in Brazil, for predicted values, as well as for the lower limit of normality, particularly in children with self-reported black or brown skin.

Conclusions:

New spirometric equations were generated for Brazilian children 3-12 years of age, in the three skin-color categories defined. The equations currently in use in Brazil seem to underestimate the lung function of Brazilian children 3-12 years of age and should be replaced by the equations proposed in this study.

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.

Influence of Socioeconomic and Anthropometric Factors on Respiratory Function in Female University Students

The purpose of this study was to evaluate lung function in healthy young female university students and to seek the relation of lung function to socioeconomic and anthropometric indices. The methodology consisted of spirometry tests, anthropometric measures and a questionnaire conducted in November of 2015 among 152 female university students. At first, lung function was analyzed for any relationship with socioeconomic factors and smoking. The results of a multi-factor analysis of variance demonstrate significant differences in the FEV1/FVC ratio depending on the general socioeconomic status. Then, anthropometric and spirometric parameters were tested for correlations. A comparison of underweight, normal weigh, overweight, and obese subjects revealed statistically significant differences for FVC% and FEV1/FVC, with the highest values noted in the subjects of normal weight. Individuals with abdominal obesity had lower FVC% and FEV1% and a higher FEV1/FVC ratio. The findings of our study confirm that both general obesity and abdominal obesity are related to a reduced lung function.

PAI-1 gain-of-function genotype, factors increasing PAI-1 levels, and airway obstruction: The GALA II Cohort

BACKGROUND

PAI-1 gain-of-function variants promote airway fibrosis and are associated with asthma and with worse lung function in subjects with asthma.

OBJECTIVE

We sought to determine whether the association of a gain-of-function polymorphism in plasminogen activator inhibitor-1 (PAI-1) with airway obstruction is modified by asthma status, and whether any genotype effect persists after accounting for common exposures that increase PAI-1 level.

METHODS

We studied 2070 Latino children (8-21y) with genotypic and pulmonary function data from the GALA II cohort. We estimated the relationship of the PAI-1 risk allele with FEV1/FVC by multivariate linear regression, stratified by asthma status. We examined the association of the polymorphism with asthma and airway obstruction within asthmatics via multivariate logistic regression. We replicated associations in the SAPPHIRE cohort of African Americans (n=1056). Secondary analysis included the effect of the at-risk polymorphism on postbronchodilator lung function.

RESULTS

There was an interaction between asthma status and the PAI-1 polymorphism on FEV₁ /FVC (P=.03). The gain-of-function variants, genotypes (AA/AG), were associated with lower FEV₁ /FVC in subjects with asthma (β=-1.25, CI: -2.14,-0.35, P=.006), but not in controls. Subjects with asthma and the AA/AG genotypes had a 5% decrease in FEV₁ /FVC (P<.001). In asthmatics, the risk genotype (AA/AG) was associated with a 39% increase in risk of clinically relevant airway obstruction (OR=1.39, CI: 1.01, 1.92, P=.04). These associations persisted after exclusion of factors that increase PAI-1 including tobacco exposure and obesity.

CONCLUSIONS AND CLINICAL RELEVANCE

The decrease in the FEV₁ /FVC ratio associated with the risk genotype was modified by asthma status. The genotype increased the odds of airway obstruction by 75% within asthmatics only. As exposures known to increase PAI-1 levels did not mitigate this association, PAI-1 may contribute to airway obstruction in the context of chronic asthmatic airway inflammation.