Association between Household Income and Allergy Development in Children: The Japan Environment and Children's Study

Background: Socioeconomic status has been found to be associated with allergic diseases in children, but results are inconsistent. This study aimed to assess the association between household income and the development of allergic disease in children at 3 years old. Methods: We used data from 72,180 participants from the Japan Environment and Children's Study, which is a prospective birth cohort study with participants recruited from January 2011 to March 2014. We examined the associations between household income and allergic diseases (asthma, eczema, and food allergies) in children, adjusting for covariates using multivariate logistic regression. Results: The percentages of doctor-diagnosed allergies at 3 years old were 7.5% for asthma, 7.2% for eczema, and 6.2% for food allergies. Children from households with an annual income of <2 million yen (approx. 18,000 USD) had a significantly higher risk of doctor-diagnosed asthma and eczema than those from households with an income of 4-6 million yen. The adjusted odds ratios (aORs) were 1.17 (95% confidence interval [CI] 1.03-1.34) and 1.21 (95% CI 1.06-1.39). Children from households with an income of >6 million yen tended to have an increased risk of food allergies (aOR 1.07, 95% CI 0.98-1.15). Conclusion: Low household income was a risk for doctor-diagnosed asthma and eczema, suggesting that public health professionals should recognize low-income groups as vulnerable populations for these conditions. </p>