Greater Understanding of Eczema’s Prevalence Needed to Improve Treatment, Prevention

Having more information on how and why the global prevalence of eczema is so heterogeneous—with both decreases and increases seen over a 10-year period—accounting for income and region, should help to better inform prevention strategies, determined an analysis published today in Clinical & Experimental Allergy.

“Gaining insight into global trends over time is a major priority, as it might provide insight into risk factors amenable to public health intervention,” the study authors wrote. “These changes in eczema prevalence over time are important, not only from a health services perspective, but also in terms of understanding eczema etiology, which is critical if we want to intervene to reduce the global prevalence and severity burden.”

Data were collected over a 5-year period (2015-2020) on 122,268 children aged 6 to 7 years (n = 47,907) and adolescents aged 13 to 14 years (n = 74,361) who received eczema care at 27 centers from 14 countries that participated in the Global Asthma Network (GAN) Phase 1 study (2015-2020), the ISAAC Phase 1 study (1993-1995), and the ISAAC Phase 3 study (2001-2003). These data were used to estimate 10-year eczema prevalence rates by age group, income, and region. GAN resulted from the ISAAC study, with a mean 15.4 years elapsing between ISAAC Phase 3 and GAN Phase 1 and 22.7 years between ISAAC Phase 1 and GAN Phase 1.

A questionnaire was distributed as part of GAN, and there were overall response rates of 90% among the adolescents in the present analysis and 79% among the children.

The median overall presence of eczema was 6%, with more adolescents than children reporting severe cases (1.1% vs 0.6%). Over a 27-year follow-up period (1993-2020), the 10-year increases were small for both eczema and severe eczema:

• Eczema:
  • Adolescents: 0.98% (95% CI, 0.04%-1.92%)
  • Children: 1.21% (95% CI, 0.18%-2.24%)
• Severe eczema:
  • Adolescents: 0.26% (95% CI, 0.06%-0.46%)
  • Children: 0.23% (95% CI, 0.02%-0.45%)

However, there were larger increases in lifetime prevalence among the 2 age groups: 3.91% (95% CI, 2.07%-5.75%) for children and 2.71% (95% CI, 1.10%-4.32%) for adolescents. Modelling that considered each age group separately produced similar findings, noted the authors.

As for prevalence, eczema symptoms ranged from a decrease of 8.9% to an increase of 4.8% among adolescents, and from a drop of 9.6% to a jump of 5.7% among children.

When income was considered, increases in most outcomes were seen only among children in high-income countries:

• Current eczema symptoms: 2.41% (95% CI, 0.87%, 3.95%)
• Severe eczema: 0.32% (95% CI, –0.02% to 0.66%)
• Lifetime eczema prevalence: 7.46% (95% CI, 4.77%-10.14%)

Among adolescents, increases were seen for just lifetime prevalence (2.32%; 95% CI, 0.40%-4.25%) and severe eczema symptoms (0.71%; 95% CI, 0.29%-1.14%) in lower–middle income countries, and for lifetime prevalence in upper–middle income countries (3.93%; 95% CI, 0.96%-6.89%).

“There was no evidence against an overall linear trend in current eczema symptom prevalence, across the whole time period (P = .87),” the study authors wrote. “There was, however, a visual indication that rates of change may be different in some groups between ISAAC Phase 1 to 3 and ISAAC Phase 3 to GAN Phase 1.”

Overall, they note that their results indicate a substantial eczema burden in most settings, but that substantial heterogeneity exists in the change estimates that can’t be fully explained by the World Bank income groups used for their analysis. In addition, they noted potential contributions from environmental causes and gene-environmental interactions; for example, skin barrier changes in infancy that precede eczema development.

“More understanding of why the prevalence of eczema is increasing in some settings is a major priority,” the authors concluded. “From a health services and disease burden perspective, there is a need to focus research efforts on understanding why the prevalence of severe eczema symptoms is particularly high in specific geographical locations.”

Reference

Langan SM, Mulick AR, Rutter CE, et al; Network Phase 1 Study Group. Trends in eczema prevalence in children and adolescents: a Global Asthma Network Phase I Study. Clin Exp Allergy. Published online February 8, 2023. doi:10.1111/cea.14276