Neighborhood Factors in Childhood May Influence Asthma Risk

Living in neighborhoods with high or very high opportunity in early life was associated with lower childhood asthma incidence compared with living in neighborhoods with low opportunity, according to a nationwide cohort study using data from the Environmental Influences on Child Health Outcomes (ECHO) Program.

Compared with a very low Child Opportunity Index (COI), the adjusted incidence rate ratio (IRR) for asthma was 0.87 (95% CI 0.75-1.00) for neighborhoods with a high COI at birth and 0.83 (95% CI 0.71-0.98) for those with a very high COI at birth, reported Izzuddin M. Aris, PhD, of Harvard Medical School and Harvard Pilgrim Health Care Institute in Boston, and co-authors.

"These associations appeared to be attributable to the health and environmental and the social and economic domains of the COI," they noted in JAMA Pediatrics.

However, the Social Vulnerability Index (SVI) during early life was not significantly associated with asthma incidence. Compared with a very high SVI, the adjusted IRR for asthma was 0.88 (95% CI 0.75-1.02) for low SVI at birth and 0.89 (95% CI 0.76-1.03) for very low SVI at birth.

The COI, originally developed in 2014 and updated in 2020, is a census-derived index that includes 29 specific neighborhood attributes across three domains -- education, health and environment, and social and economic.

The SVI is a similar tool that examines 15 social factors across four domains -- socioeconomic status, household composition and disability, racial and ethnic minority and language status, and housing and transportation type. The SVI "was developed primarily for emergency preparedness in the event of a disaster; thus, it might be less sensitive to childhood asthma," the authors pointed out.

Aris and team noted that their results are in line with prior studies in children that examined neighborhoods and asthma, with two studies showing that children born in neighborhoods with greater walkability or with greener environments had lower risk of incident asthma in childhood.

The findings may be "partly explained by higher childhood BMI, which is an established factor associated with incident asthma and was previously shown to be more prevalent in ECHO children residing in neighborhoods with lower opportunities," they pointed out.

"Residence in more advantageous neighborhoods has been associated with higher physical activity levels and healthier eating patterns in children, which in turn, are associated with lower asthma risk, likely through reduced airway inflammation," they added. "Residence in neighborhoods with more favorable opportunities also likely reduces early life exposure to traffic-related air pollutants, which are known to be associated with subsequent asthma development in children."

For this study, Aris and colleagues used data on children in 46 cohorts participating in the ECHO Program from January 1995 through August 2022. Participants were followed up to the date of asthma diagnosis, date of last visit or loss to follow-up, or age 20 years. The main outcome was parent or caregiver report of a physician's diagnosis of childhood asthma.

COI and SVI were grouped into "very low" (<20th percentile), "low" (20th to <40th percentile), "moderate" (40th to <60th percentile), "high" (60th to <80th percentile), or "very high" (80th percentile) categories.

The researchers included a total of 10,516 children in the study. Median age at follow-up was 9.1 years, 52.2% were boys, 65.3% were white, 18.5% were Black, and 15% were Hispanic.

Of these kids, 20.6% lived in neighborhoods categorized as having a very high COI and a very low SVI. The overall asthma incidence rate was 23.3 cases per 1,000 child-years. Median age at asthma diagnosis was 6.6 years.

Aris and colleagues noted that their findings may be subject to recall bias, since they relied on parent/caregiver report of physician-diagnosed asthma for their outcome. In addition, they used residential census tracts as a marker of exposure, "which may not capture relevant areas where children spend most of their time," they wrote.

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