Exploring the Impact of Household Income and Maternal Education on Childhood Asthma
The prevalence of childhood asthma varies widely across different regions of the world, with wide-ranging implications for children’s health and wellbeing. Emerging research indicates that a child’s early socioeconomic status (SES), measured by factors like household income and maternal education, can have a significant influence on their risk of developing asthma and experiencing related symptoms.
By examining the associations between early family SES and asthma-related outcomes in children aged 9-12 years across six high-income countries, this article aims to provide valuable insights for healthcare professionals, policymakers, and community advocates. Understanding these social inequalities is crucial for developing effective prevention strategies and ensuring equitable access to asthma management resources.
The Scope of Childhood Asthma Globally
Asthma is one of the most common chronic conditions affecting children worldwide. Respiratory symptoms like wheezing, shortness of breath, and persistent cough are key indicators of asthma in epidemiological studies. Global data from the International Study of Asthma and Allergies in Childhood (ISAAC) reveals wide variations in the prevalence of childhood asthma and wheezing across different regions.
Between 2000 and 2003, the prevalence of children ever having asthma was 16.3% in Western Europe, 22.5% in North America, and 32.4% in Oceania. Similar disparities were observed in the prevalence of wheezing in the previous 12 months, ranging from 15.2% in Western Europe to 21.5% in North America and 26.7% in Oceania.
These substantial differences in childhood asthma and wheezing across high-income countries underscore the need to better understand the social determinants contributing to these variations. Examining the role of early family socioeconomic status can provide valuable insights to guide public health interventions and policies.
Measuring Socioeconomic Status and Asthma-Related Outcomes
A child’s socioeconomic status can be assessed through various indicators, including household income, caregiver employment, and parental education. Each of these SES variables has been previously linked to childhood asthma and related outcomes, though the findings have been inconsistent.
To facilitate robust comparisons across countries, this study focused on two key SES measures: maternal education and household income. Maternal education was harmonized using the International Standard Classification of Education (ISCED), categorizing levels as low (ISCED I-II), middle (ISCED III-IV), and high (ISCED V-VII). Household income was standardized across cohorts using purchasing power parity (PPP) to enable cross-country comparisons.
The study examined three asthma-related outcomes in children aged 9-12 years:
1. Ever asthma: whether the child had ever been diagnosed with asthma by a healthcare professional
2. Wheezing/asthma attacks: parent-reported wheezing or asthma attacks in the past 12 months
3. Asthma with medication control: ever diagnosis of asthma and use of asthma-related medication in the past 12 months
These outcomes provide a comprehensive assessment of both the presence and severity of asthma-related symptoms in the study population.
Findings from the International Birth Cohort Study
The Elucidating Pathways of Child Health Inequalities (EPOCH) study, a collaboration of seven prospective birth cohort studies across six high-income countries, examined the associations between early family SES and asthma-related outcomes in 31,210 children.
Relative Inequalities in Asthma-Related Outcomes
The pooled analysis revealed the following findings regarding relative inequalities:
Ever Asthma:
– Children from lower-income households had a 28% higher risk of ever experiencing asthma compared to those from higher-income households (RR 1.28, 95% CI 1.15-1.43).
– Children of mothers with lower educational attainment had a 24% higher risk of ever asthma compared to those with highly educated mothers (RR 1.24, 95% CI 1.13-1.37).
Wheezing/Asthma Attacks:
– Children from lower-income households had a 22% higher risk of wheezing/asthma attacks compared to those from higher-income households (RR 1.22, 95% CI 1.03-1.44).
– The association between maternal education and wheezing/asthma attacks was not statistically significant (RR 1.14, 95% CI 0.97-1.35).
Asthma with Medication Control:
– Children from lower-income households had a 25% higher risk of having asthma with medication control compared to those from higher-income households (RR 1.25, 95% CI 1.01-1.55).
– The association between maternal education and asthma with medication control was not statistically significant (RR 1.16, 95% CI 0.97-1.40).
These pooled estimates indicate that lower household income during early childhood is consistently associated with poorer asthma-related outcomes in later childhood, while the associations with maternal education are more nuanced.
Absolute Inequalities in Asthma-Related Outcomes
To provide a comprehensive understanding of social inequalities, the study also examined absolute differences in asthma-related outcomes using the Slope Index of Inequality (SII). The SII represents the absolute difference in prevalence between the most advantaged and the least advantaged groups in the population.
The analysis of absolute inequalities revealed the following key findings:
Ever Asthma:
– Except for wheezing/asthma attacks by maternal education in the UK and by income in Sweden, the absolute risk was in the expected direction for all outcomes, complementing the relative risk findings.
– The largest potential reduction in ever asthma prevalence, based on higher maternal education, would be observed in Australia (-9.76) and the Netherlands (-8.03).
– For higher household income, the largest potential reduction in ever asthma would be in Australia (-9.09), Quebec, the Netherlands, and the UK (all around -7%).
Wheezing/Asthma Attacks:
– In the UK and Sweden cohorts, children of higher maternal education had a greater risk for wheezing/asthma attacks, although the absolute differences were small.
– Among the remaining cohorts, the highest absolute inequality by maternal education for wheezing/asthma attacks was in Australia (-10.71) and the lowest was in Quebec (-1.36).
– For absolute inequality by income, the highest was in the USA (-6.38) and the lowest was in Sweden (-0.44).
Asthma with Medication Control:
– Absolute inequalities in asthma with medication control were lower than in ever asthma.
– In Sweden, children of higher maternal education had a greater risk for medication control (SII: 0.98).
– The highest absolute inequality by maternal education for medication control was in Quebec (-2.67) and the lowest was in the UK (-0.47).
– For absolute inequality by income, Canada had the highest inequality (-9.52) and Sweden had the lowest (-0.1).
These findings on absolute inequalities complement the relative risk estimates, providing a comprehensive understanding of the social gradients in asthma-related outcomes across the participating countries.
Implications for Healthcare and Policy
The results of this international study have several important implications for healthcare professionals, policymakers, and community advocates working to address childhood asthma:
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Awareness of Social Inequalities: Healthcare providers should be aware of the relatively higher risks of respiratory morbidity in children from families with low socioeconomic status. This knowledge can inform more targeted screening, education, and management strategies.
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Targeted Prevention Policies: The findings underscore the need for prevention policies and interventions to address the social inequalities in asthma-related outcomes among school-aged children. Tailored approaches that consider the unique social and economic contexts of different communities are essential.
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Improving Access to Asthma Care: Ensuring equitable access to high-quality asthma diagnosis, treatment, and management resources, particularly for families with low income and lower maternal education, is crucial for reducing the social disparities in childhood asthma.
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Addressing Social Determinants of Health: Beyond the healthcare sector, multi-sectoral collaborations and policies that address the broader social determinants of health, such as housing quality, air pollution, and access to green spaces, can help mitigate the impact of socioeconomic disadvantage on childhood asthma.
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International Collaboration and Research: The EPOCH study’s international approach demonstrates the value of cross-country collaborations in examining the complex relationships between early life SES and children’s health outcomes. Continued research and data-sharing in this area can inform more effective, evidence-based strategies to address global health inequities.
By addressing the social inequalities in childhood asthma, healthcare professionals, policymakers, and community advocates can work towards ensuring that all children have the opportunity to thrive, regardless of their family’s socioeconomic background.
Conclusion
This comprehensive analysis of seven prospective birth cohort studies across six high-income countries highlights the significant impact of early family socioeconomic status on children’s asthma-related outcomes in later childhood. The findings demonstrate that lower household income and, to a lesser extent, lower maternal education are associated with increased relative and absolute risks of ever asthma, wheezing/asthma attacks, and asthma with medication control.
These insights underscore the need for targeted prevention policies, equitable access to high-quality asthma care, and multi-sectoral interventions that address the broader social determinants of health. By working collaboratively to tackle the social inequalities in childhood asthma, we can empower all children to breathe easier and thrive, regardless of their family’s socioeconomic background.
