Racial Disparities in Allergic Outcomes Persist to Age 10 Years in Black and White Children

Numerous studies have demonstrated racial disparities in allergy and asthma outcomes. In the WHEALS birth cohort from Detroit, MI, Black children were more likely to experience allergic outcomes, such as atopic dermatitis, at least 1 positive skin prick test, and at least 1 positive allergen-specific immunoglobulin E (IgE), at the age of 2 years when compared with white children. These differences persisted even after adjusting for potential socioeconomic confounders such as income, education, or pet keeping. The purpose of this study was to assess the WHEALS birth cohort at age 10 and evaluate if the previously observed racial disparities persisted.

The study included 481 children from Detroit, MI, enrolled in the WHEALS birth cohort, a cohort where mothers were not recruited based on parental history of allergic diseases.

Children who participated in the WHEALS birth cohort were invited for a clinic visit at 10 years of age during which history, physical exam, spirometry with methacholine challenge, skin prick testing (SPT), and blood draw measuring total IgE and a panel of 10 food and inhalant allergen-specific IgE (sIgE) were performed. Additional variables (baseline covariates, confounders, effect modifiers) were considered including income, education, location of residence, breastfeeding history, tobacco exposure, and birth history (prenatal exposures, maternal obesity, mode of delivery, season of delivery, gestational age, etc). Linear and logistic regression models were used to determine associations between race and outcomes. To account for loss to follow-up, inverse probability weights were calculated using covariates above to determine inclusion in regression models.

481 children of the 1053 enrolled in WHEALS were included in this study. Analysis of those included and excluded for analysis due to loss of follow-up demonstrated no significant difference between groups after inverse probability weighting. In the unadjusted analysis of binary outcomes, Black children were more likely to be sensitized to 1 or more sIgE (odds ratio [OR]: 1.9, 95% confidence interval [CI]: 1.2–2.9), have eczema (OR: 2.9, 95% CI: 1.5–5.8), and have asthma (OR: 4.8, 95% CI: 2.2–10.3). After imputation and full covariate adjustment, these associations remained the same, with the addition that Black children were more likely to have positive methacholine challenge at <25 mg/mL compared with white children (OR: 2.1, 95% CI: 1.2–3.9). In the unadjusted analysis of continuous variables, such as total IgE and spirometry measures, only total IgE was statistically significant in association with race, where the geometric mean of total IgE was 86% higher in Black children compared with white children. After imputation and full covariate adjustment, the percentage predicted forced vital capacity was higher in Black children compared with white children and statistically significant.

Racial differences persisted in allergic outcomes between Black and white children through 10 years of age, and the assessed confounding factors could not explain these differences.

This study adds to the growing body of literature highlighting racial disparities in allergic outcomes after adjusting for confounders. Identifying the source of these disparities has been challenging, and further studies are needed to assess the impact of possible contributing factors such as toxic and non-toxic exposures or disparate social structures resulting in these reproducible findings.