Socioeconomic determinants of asthma health

Structured abstract:

Purpose of review:

This review provides an assessment of the recent pediatric literature evaluating socioeconomic drivers of asthma incidence and morbidity. The review addresses the specific social determinants of health related to housing, indoor and outdoor environmental exposures, health care access and quality, and the impact of systematic racism.

Recent findings:

Many social risk factors are associated with adverse asthma outcomes. Children living in low-income, urban neighborhoods have greater exposure to both indoor and outdoor hazards including molds, mice, second-hand smoke, chemicals, and air pollutants, all of which are associated with adverse asthma outcomes. Providing asthma education in the community—via telehealth, school-based health centers, or peer mentors—are all effective methods for improving medication adherence and asthma outcomes. The racially segregated neighborhoods created by the racist “redlining” policies implemented decades ago, persist today as hotspots of poverty, poor housing conditions, and adverse asthma outcomes.

Summary:

Routine screening for Social Determinants of Health in clinical settings is important to identify the social risk factors of pediatric patients with asthma. Interventions targeting social risk factors can improve pediatric asthma outcomes, but more studies are needed related to social risk interventions.

Introduction

Pediatric asthma preferentially impacts children of color and socioeconomic disadvantage¹. Black Americans are 5 times more likely to have an ED visit for asthma and 3 times more likely to die from asthma². Consideration of the social determinants of health (SDOH) and addressing socioeconomic disparities is critical in order to improve clinical outcomes. The United Stated (US) Office of Disease Prevention and Health Promotion groups SDOH into five domains—economic stability, education access and quality, health care access and quality, neighborhood and built environment, social and community context³. In this review, we will summarize recent literature on three specific domains related to socioeconomic disparities—environmental exposures, medical care delivery, and systemic racism – on childhood asthma prevalence and morbidity (Figure 1).

Figure 1.

Concentric Venn diagram of socioeconomic determinants of health affecting childhood asthma

Environmental risk

Socioeconomic risk factors for asthma are mediated by exposures to allergens, pollutants, and household contaminants that are prevalent in disadvantaged communities in the US; biomass fuel is a more prevalent risk factor worldwide⁴. Structural disadvantage and racist practices have led to low quality housing stock, vulnerable to pest infestation, in areas of high traffic density, close proximity to industrial areas, and lower access to healthy foods, as the only affordable options for many families. Stress and other SDOH mediate the relationship between environment, environmental injustice, and asthma in children⁵. Public schools in these communities suffer similar environmental conditions and serve as an important location of exposure and potential site for remediation.

Indoor exposures

Indoor environmental hazards include air pollutants, allergens, molds, and chemicals⁶. Recent studies have identified early life exposure to cockroach and mouse allergens⁷ and allergen and bacterial diversity⁸ can be protective for developing wheeze and atopy, suggesting tolerance may occur; however allergens remain triggers for previously sensitized asthmatics. While house dust mite is ubiquitous, mouse and cockroach allergens, as well as molds, are commonly found in urban homes and schools. Mouse allergen reduction has been a recent focus of intervention. The Mouse Allergen and Asthma Intervention Trial (MAAIT)⁹, a home-based integrated pest management trial, found that decreased mouse allergen was associated with improved asthma outcomes. Akar-Ghibril, et al. found that higher level of mouse allergen levels at baseline, evidence of rodent holes, and greater proportion of clear floor space in the child’s bedroom predicted 90% reduction in mouse allergen after intervention¹⁰. Children living in environments with lower particulate matter (PM) had greater symptomatic response to mouse allergen reduction¹¹. Urban school exposure to mouse allergen has also been associated with increased asthma symptoms¹². However, a recent randomized school based integrated pest management (IPM) and air purifier intervention trial found early improvement in asthma outcomes with IPM that were not sustained throughout the school year¹³. A qualitative study of the Collaboration to Lessen Environmental Asthma Risks (CLEAR) program, a home visit program to provide education and recommend home remediation, identified that providers and mothers, alike, value the additional asthma education and advocacy for home improvements, but mistrust of health department staff may be potential barrier to optimal implementation home-based community interventions¹⁴. Air purifiers benefit both indoor air quality and asthma symptoms in children, typically as part of a multipronged approach. A recent study identified high adherence to air purifier interventions for children with asthma in low-income urban neighborhoods¹⁵, with winter season as a key factor for non-adherence. Despite extensive data detailing allergen and pollutant risk factors in the personal environment, identifying and implementing successful intervention strategies remains an unmet need.

Second-hand tobacco smoke exposure is higher in inner-city low-income households¹⁶. Data from the school inner city asthma study recently found children of lower income households, non-white race, and Hispanic ethnicity had higher urinary cotinine levels that were associated with worse asthma symptoms and increased exacerbations¹⁷.

Urban homes and schools have high mold exposures^{18, 19} which is associated with severe asthma, poor symptom control, and frequent exacerbations. Mucor was higher in homes of children with difficult to treat asthma in the Asthma Phenotypes in the Inner City (APIC) study compared concentrations in homes of children with easy to treat asthma²⁰. Homes with window air conditioning units are particularly susceptible to high Mucor levels.

Building materials, personal care products and cleaning agents produce volatile organic compounds (VOCs) and are associated with increased asthma exacerbations in children²¹. Even preconception and prenatal exposures in mothers with occupational exposure to cleaning agents is associated with 1.5 – 2.25 odds of offspring asthma or wheeze²². VOCs may affect asthma development and exacerbations by disrupting bronchial epithelial integrity or immunoregulatory function, enhancing allergen sensitization or increasing bronchoreactivity in sensitized individuals²³.

Emerging indoor exposures

Phthalates are synthetic chemicals used as solvents and plasticizers in personal hygiene products, cosmetics, toys, medical equipment and medications, building materials, and food and drink containers²⁴. Phthalate biomarker concentrations are greater in children of low-income families compared to the general US population, likely due to impaired access to fresh foods and greater consumption of processed, canned or bottled food products. Phthalates, along with Bisphenol A (BPA), another synthetic chemical found in consumer goods, are strongly associated with worsened asthma symptoms and greater healthcare utilization via ED, acute care, and unscheduled doctor visits²⁵.

Radon gas is a known carcinogen derived from decay of uranium in the earth’s crust, but recent data suggests it may have non-carcinogenic adverse health effects in adults. Mukharesh et al. recently reported short-term exposure to residential radon levels was associated with increased frequency of asthma diagnosis and twice the odds of school absenteeism among inner-city children²⁶, suggesting radon may have a role in asthma pathogenesis and morbidity.

Outdoor exposures

Ambient environmental exposures also differentially affect asthmatic children in low-income, urban environments, primarily due to air pollution in the form of nitrogen dioxide (NO₂) and PM generated by traffic or industrial processes^{19, 23, 27, 28}. Anenberg and colleagues utilized land use regression models to estimate incident asthma globally in 2019 by scaling exposure models based on over 5000 NO₂ monitors in 58 countries²⁹. Urban areas accounted for 2/3 of the cases of pediatric asthma and, though improved from 19.8% in 2000, 16% of cases were attributable to NO₂. Historical inequity has led Black and low-income families to reside in areas with higher PM_2.5 concentrations³⁰, which are associated with increased asthma symptoms, urgent and emergency room visits^{23, 28, 31}. Komisarow and Pakhtigian found that the closure of 3 coal-fired powerplants in the Chicago area led to a 12%−18% reduction in ED visits for asthma exacerbations³². Approximately 7% of all children between 0 and 4 years of age in the US still live within 10-kilometers of an active coal-fired power plant.

Recent application of geospatial models of social disadvantage to pediatric intensive care admissions and readmissions identified hotspots within Georgia where social vulnerability and low social opportunity was associated with life threatening asthma exacerbations³³. Increased crowding, lower access to greenspace, and slightly higher measures of PM and pollutants in the air, water, and soil were among the hotspot characteristics. Greenness was a specific focus of a geospatial analysis performed in Palermo, Italy, which also found strong association between low greenness (defined by standardized measure of normalized difference vegetation index (NDVI) from satellite imaging) and uncontrolled asthma³⁴, independent of local traffic and NO₂ exposures.

Emerging data suggests that climate change may directly impact childhood asthma risk. A retrospective cohort study of 39,782 children in cities throughout China found that prenatal and postnatal heat exposure was associated with greater risk of childhood asthma³⁵. Children living in inner-city low income neighborhoods are again at a disadvantage for heat exposure due to sparse canopy and greater paved surfaces³⁶. Investigators at the Children’s Hospital of Philadelphia examining 7,637 encounters for asthma found greater asthma exacerbations associated with higher daily temperatures in preschool-aged children³⁷. Notably, this study population was composed of predominantly Black children (81%) on Medicaid and State Children’s Health Insurance Program.

Simply summarized, low socio-economic communities suffer greater exposure to pollutants which directly contribute to adverse asthma outcomes. Improved air quality, education, and housing conditions as part of a larger policy to improve social and economic justice is important to improve asthma in impoverished and minoritized children.

Social Disparity and Care Delivery

Education

The NAEPP EPR-3 guidelines recommend asthma education as a key element of quality asthma care³⁸. Recent studies focused on identifying the best location and method for providing asthma education, and medication adherence.

Asthma education is typically provided in the clinic as part of routine visits or in the inpatient setting during an asthma exacerbation. However, this approach requires 1) patients attend clinic or be admitted to the hospital and 2) the ability to receive and comprehend the information in a relatively short period of time. Providing culturally-specific education is important and effective³⁹. In a randomized-controlled, multi-center study for adolescents with asthma comparing asthma education delivered by a peer-leader versus an adult, Rhee at al found significantly improved asthma control, quality of life, and self-efficacy in the peer-leader group⁴⁰. Both groups showed improvement in asthma outcomes, reinforcing the value of community-based asthma education. Zheang et al.⁴¹ explored African American and LatinX caregiver asthma knowledge and perceptions and response to informational materials. They found that caregivers worry more about acute exacerbations and emergencies, less about daily impairment, were uncomfortable with daily controller medication use, and were unable to identify uncontrolled asthma in their own children after reviewing messaging materials. While a small study (19 caregivers), it provides useful information about the priorities and concerns of families, which can then allow for the development and delivery of targeted and culturally appropriate education and care.

School-based asthma management programs continue to show promising results for improving asthma outcomes. Holmes et al. performed a pilot study of a multifaceted asthma management program implemented in school-based health centers in high poverty schools⁴². The school-based health center providers received education in guideline-based asthma management and the students in the intervention received directly observed therapy, adjustment in medications, and self-management education. Those receiving the intervention were much more likely to undergo a step-up in asthma therapy, indicating potential benefits of providing asthma care in the school setting, which overcomes many barriers families face seeking attending clinical appointments.

Adherence

Medication adherence is another important aspect of asthma self-management. Poor asthma medication adherence is a significant contributor to adverse asthma outcomes⁴³. Recently, Mamman et al.⁴⁴ showed significant improvement in asthma control and medication adherence for adults utilizing a smartphone-based telemedicine approach which integrated electronic symptom monitoring, nurse telemedicine visits, and clinician guideline-based asthma-management support. For children, who may not have access to a smartphone, administration of controller medications in the school setting is another way to successfully improve medication adherence⁴².

Measuring adherence outside of a study setting remains a challenge. Margolis et al. found that the five-item medication adherence report scale completed by caregivers of low-income, urban, African American youth with poorly controlled asthma did not correlate with markers of asthma control or the Asthma Medication Ratio⁴⁵, supporting prior findings that self-report is not a reliable way to measure medication adherence.

Resource needs for asthma patients

The onset of the COVID-19 pandemic required pediatricians and pediatric subspecialists to provide care via telemedicine. Telemedicine can be an effective platform for providing asthma education, but socioeconomically disadvantaged families may not have access to a device or stable internet, thus widening the healthcare disparity gap. Justvig et al.⁴⁶ described their experience pivoting to telemedicine for patients with asthma in an urban primary care practice at the beginning of the pandemic. Overall, it was well-received by patients who expressed a positive experience with telemedicine, and 1/5 families received assistance with a resource related to transportation, food and supplies, clothing, utilities, and rent. Telemedicine may be a convenient way to provide frequent and targeted assessments focused on addressing the SDOH.

Schechter et al.⁴⁷ implemented the use of Community Health Workers (CHW) to perform SDOH screening after discharge for hospitalized pediatric patients. They found very high rates of food and housing insecurity (50% reporting either one), 63% reporting poor housing conditions, 94% of the families had at least 1 social risk factor present, and 99% received assistance from the CHW with social resource navigation. This study supports the importance of SDOH screening in the inpatient setting, particularly for pediatric patients hospitalized for asthma.

Systemic Racism and Asthma Risk

Racism is an important determinant impacting child health⁴⁸. Race, ethnicity, and poverty, combined with the contributions of interpersonal, institutional, and public policy racism, make it difficult to tease apart the contribution of individual SDOH elements. Asthma prevalence increases as poverty levels decrease, and poverty independently has been associated with adverse asthma outcomes¹⁹. The geospatial “hotspots” identified by Grunwell et al,³³ also line up with the segregated neighborhoods created by historical “redlining”^{49, 50}. These segregated neighborhoods have also been associated with decreased access to healthcare facilities and primary care providers, along with decreased educational opportunities^{51, 52}. This suggests that the racist public policies and practices implemented almost 100 years ago continue to create areas of social vulnerability, limited opportunity, and poor health outcomes. Several studies have further explored the structural and social risks associated with adverse asthma outcomes^53–56. Experiencing discrimination, along with markers of poverty, exposure to violent crime, and caregiver educational attainment are all associated with increased healthcare utilization for children with asthma. Tyris et al.⁵⁶, utilizing the National Survey of Children’s Health, identified 14 social risks associated with increased asthma utilization. The highest adjusted odds ratios were found for families experiencing discrimination, receiving free/reduced lunch, and being a victim of violence. Using the same survey data, Alachraf et al.⁵³ identified race/ethnicity, insurance coverage, and caregiver educational attainment to be associated with ED visits for pediatric asthma; these factors did not vary by asthma severity. Similarly, decreased educational attainment and violent crime were found to be associated with at-risk rates of asthma⁵⁵. Mersha et al.⁵⁴ explored pediatric asthma readmissions from the lens of African genetic ancestry versus the social constructs associated with race. Increasing African genetic ancestry was associated with increased risk of re-admission, but this association was mediated by socioeconomic factors. The strongest socioeconomic factors were hardship and disease management, specifically, children sleeping away from home routinely without access to their medications. This study provides important insight into the socioeconomic contributors to pediatric asthma readmissions and may inform future targets for socioeconomic intervention studies.

Conclusion:

Asthma differentially affects children from low socioeconomic and minoritized communities. Many studies identify associations between individual and community-level social determinants and asthma prevalence and morbidity. Fewer data support interventions to address these disparities, leaving an important gap to be filled in improving asthma outcomes in children.

Key Points:

1. Children living in poor, urban neighborhoods experience higher levels of indoor and outdoor exposures that are associated with adverse asthma outcomes.

2. Providing community-based, culturally sensitive asthma education can improve asthma outcomes and should be a part of routine asthma care.

3. Routine screening for SDOH should also be a part of pediatric asthma care given the high rates of social risk factors identified in children with asthma, and the association of these risk factors with adverse asthma outcomes.

4. More interventions, both policy and clinical, are needed to overcome the continuing impact of redlining in the creation of segregated, poor neighborhoods, with the highest rates of adverse pediatric asthma outcomes.