Childhood obesity may increase the risk of immune-mediated skin diseases, with a 15% higher incidence of atopic dermatitis among overweight children, according to a study of over 2 million South Korean children.

Children with increased body mass index (BMI) had a 15% higher risk of developing atopic dermatitis, along with elevated risks for alopecia areata and psoriasis, according to a recent study. The large-scale longitudinal cohort study involving over 2 million South Korean children, conducted from 2009 to 2020, has demonstrated an association between childhood obesity and the risk of developing immune-mediated skin diseases (IMSDs), including alopecia areata (AA), atopic dermatitis (AD), and psoriasis. An elevated BMI in early childhood was linked to a higher incidence of these dermatologic conditions.

Throughout the study period, researchers recorded 4,878 cases of AA, 41,386 cases of AD, and 2,191 cases of psoriasis. Children classified as overweight (BMI in the 85th–94th percentile) faced a higher risk of developing AD compared to those with a normal BMI (5th–84th percentile) (adjusted hazard ratio [aHR] = 1.13; 95% confidence interval [CI], 1.10–1.17). Additionally, children who were obese (BMI ≥ 95th percentile) exhibited an increased risk for all examined IMSDs, including AA (aHR = 1.15; 95% CI, 1.02–1.29), AD (aHR = 1.12; 95% CI, 1.08–1.17), and psoriasis (aHR = 1.24; 95% CI, 1.05–1.47).

The analysis revealed that an increase in BMI is associated with an increased risk of AD, with children transitioning from a normal to overweight BMI category experiencing a 15% increased risk of developing AD compared to those who maintained a normal BMI (aHR = 1.15; 95% CI, 1.11–1.20). Conversely, children who reduced their BMI from overweight to normal demonstrated a 13% reduction in AD risk compared to children who remained overweight (aHR = 0.87; 95% CI, 0.81–0.94). These findings, published in the Journal of Investigative Dermatology, indicate that BMI management during early childhood may influence the risk of AD. The increased risks for IMSDs in children who were overweight or obese were generally consistent across different subgroups, such as sex, breastfeeding history, household income, and birth weight.

Sensitivity analyses conducted with data from various health screenings, such as the third screening at 18-24 months and the fourth screening at 30-36 months, supported the primary results, showing consistent patterns in the relationship between BMI changes and the risk of IMSDs. Additionally, the study evaluated a negative control outcome, specifically melanocytic nevus, and identified no significant link with BMI or changes in BMI, supporting the reliability of the main analyses by confirming the lack of observational bias.

This study faced several limitations. The retrospective design limited the ability to account for all potential confounding factors, such as maternal health and birth details, highlighting the need for further research incorporating parental and child data. Additionally, reliance on BMI as the sole measure of obesity may not fully capture body composition, as the authors noted the lack of other measures like body fat percentage as a limitation. The use of international diagnostic codes could have also led to some disease misclassification. Lastly, the study population consisted of children who voluntarily participated in health screenings, potentially leading to a sample with higher income and health awareness, which calls for further studies with more diverse populations to validate these findings.

Although the research establishes a strong correlation between increased BMI and the development of these conditions, the study design precludes drawing definitive conclusions about causality, highlighting the need for further investigation into the pathophysiological mechanisms involved. Full disclosures can be found in the published study.