Climatic Factors Are Associated with Childhood Eczema Prevalence in the United States

Abstract

Atopic dermatitis (AD, atopic eczema) is driven by a complex relationship between genetic predisposition and environmental exposures. We sought to determine the impact of specific climatic factors on the US prevalence of AD. We used a merged analysis of the 2007 National Survey of Children's Health from a representative sample of 91,642 children age 0–17 years and the 2006–2007 National Climate Data Center and Weather Service measurements of relative humidity (%), indoor heating degree days (HDD), clear sky UV indices ozone levels, and outdoor air temperature. As a proxy for AD, we used an affirmative response to the NSCH survey question asking whether the participant’s child has been given a doctor diagnosis of “eczema or any other kind of skin allergy” in the previous 12 months. In multivariate models controlling for sex, race/ethnicity, age and household income, eczema prevalence was significantly lower with highest-quartile mean annual relative humidity (logistic regression, adjusted odds ratio [95% confidence interval]=0.82 [0.71–0.96], P=0.01) and issued UV index (0.73 [0.64–0.84], P<0.0001), and with two other factors associated with increased UV exposure. Eczema prevalence was decreased with highest-quartile air temperature (0.80 [0.70–0.92], P=0.002), but increased with 3rd–quartile mean annual HDD (1.26 [1.11–1.43], P=0.0003). This study provides evidence of climate influences on the US prevalence of childhood eczema.