Global Associations between UVR Exposure and Current Eczema Prevalence in Children from ISAAC Phase Three

Abstract

We sought to examine the relationship globally between UVR dose exposure and current eczema prevalences. ISAAC Phase Three provided data on eczema prevalence for 13- to 14-year-olds in 214 centers in 87 countries and for 6- to 7-year-olds in 132 centers in 57 countries. Linear and nonlinear associations between (natural log transformed) eczema prevalence and the mean, maximum, minimum, standard deviation, and range of monthly UV dose exposures were assessed using linear mixed-effects regression models. For the 13- to 14-year-olds, the country-level eczema prevalence was positively and linearly associated with country-level monthly mean (prevalence ratio = 1.31 [95% confidence interval = 1.05-1.63] per kJ/m) and minimum (1.25 [1.06-1.47] per kJ/m) UVR dose exposure. Linear and nonlinear associations were also observed for other metrics of UV. Results were similar in trend, but nonsignificant, for the fewer centers with 6- to 7-year-olds (e.g., 1.24 [0.96-1.59] per kJ/m for country-level monthly mean UVR). No consistent within-country associations were observed (e.g., 1.05 [0.89-1.23] and 0.92 [0.71-1.18] per kJ/m for center-level monthly mean UVR for the 13- to 14- and 6- to 7-year-olds, respectively). These ecological results support a role for UVR exposure in explaining some of the variation in global childhood eczema prevalence.

The effects of season and weather on healthcare utilization among patients with atopic dermatitis

“…28 AD prevalence is inversely associated with sunlight exposure, 29 and the strong correlation between latitude and AD is likely secondary to differences in ultraviolet exposure. 8 Our findings are complementary to these prevalence data; a decrease in 50 h of bright sunlight over the course of a month correlated with an increase of~134 TCI prescriptions. These results parallel the effects of cloud cover on healthcare utilization: a 10% increase in cloud cover correlated with an increase of~9 hospital/clinic monthly visits for AD and ~262 TCI prescriptions.…”

“…It has been proposed that decreased environmental ultraviolet light exposure may be an important driver of the global increasing AD prevalence . AD prevalence is inversely associated with sunlight exposure,and the strong correlation between latitude and AD is likely secondary to differences in ultraviolet exposure . Our findings are complementary to these prevalence data; a decrease in 50 h of bright sunlight over the course of a month correlated with an increase of ~134 TCI prescriptions.…”

“…Reductions in humidity, temperature and ultraviolet light negatively affect the skin barrier . Accordingly, neonatal AD was associated with winter birth in northern European countries, and AD prevalence is higher in countries distant to the equator . Seasonal changes and weather may also influence the risk of AD flares and disease severity.…”

Atopic dermatitis: the skin barrier and beyond

“…An autumn–winter birth has also been associated with an increase in AD prevalence, and a U.S. study found that AD prevalence was higher in areas with more indoor heating, lower relative humidity, lower mean temperatures, higher precipitation and lower ultraviolet index . Most recently, a worldwide ecological analysis using ISAAC (The International Study of Asthma and Allergies in Childhood) phase III data reported a positive linear association between country‐level AD prevalence and certain metrics of ultraviolet radiation exposure, and nonlinear relationships with other metrics of ultraviolet radiation exposure. These associations were significant among 13–14 year olds, but not in 6–7 year olds.…”

The exposome in atopic dermatitis

“…An ecological analysis of ISAAC data demonstrated a positive linear correlation between country-level monthly minimum and mean UVR exposure and AD prevalence, particularly among 13-to 14-year-olds. 18 Lower AD prevalence is also associated with areas of high relative humidity, high temperatures and low use of central heating. 19,20 Recent data from Denmark highlight that the inverse of the above weather conditions is conducive to AD flares, using healthcare utilization as a surrogate marker for exacerbations.…”