Seborrheic Dermatitis Linked to Epithelial Barrier Disorders Across Multiple Organs: JAMA
USA: Researchers have found in a retrospective cohort study that seborrheic dermatitis, a common epithelial barrier disorder (EBD) of the skin, is associated with other EBDs affecting respiratory, gastrointestinal, and ocular surfaces. These findings support the epithelial barrier theory (EBT), suggesting shared mechanisms underlying EBDs across different epithelial sites.
The study, published in JAMA Dermatology by Sabrina Meng from the Perelman School of Medicine at the University of Pennsylvania, Philadelphia, and colleagues, analyzed data from over 20 million adults to explore the relationship between seborrheic dermatitis and other epithelial barrier diseases. The EBT proposes that disruption of the epithelial barrier contributes to a variety of skin, respiratory, gastrointestinal, and ocular conditions.
The retrospective cohort study utilized data from a large U.S. administrative claims database spanning January 2016 to June 2022, including adults aged 18 years and older with at least one year of continuous enrollment and a minimum of two medical visits. Patients missing demographic details were excluded. The analysis covered a follow-up period of more than 70 million person-years.
The study revealed the following findings:
- Out of 20,274,189 patients, 733,776 (3.62%) were diagnosed with seborrheic dermatitis.
- The median age of affected individuals was approximately 63 years. Females accounted for 54.7% of the seborrheic dermatitis group.
- Seborrheic dermatitis showed significant associations with multiple epithelial barrier diseases.
- Positive associations were observed with atopic dermatitis, alopecia areata, contact dermatitis, psoriasis, rosacea, hidradenitis suppurativa, chronic spontaneous urticaria, pemphigus vulgaris, and bullous pemphigoid.
- Additional positive links were noted with rhinosinusitis, celiac disease, irritable bowel syndrome, ocular allergy, and dry eye.
- Negative associations were identified with chronic obstructive pulmonary disease (COPD) and pulmonary hypertension, suggesting differing inflammatory or barrier mechanisms in these conditions.
The authors suggested that the shared mechanisms in seborrheic dermatitis and other EBDs could stem from common disruptions in the epithelial barrier, leading to cross-organ susceptibility to inflammation. The findings strengthen the evidence supporting the EBT model, emphasizing the interconnected nature of diseases arising from barrier dysfunction across various epithelial surfaces.
While the study provides robust evidence due to its large sample size and adjusted analyses for potential confounders, the authors acknowledged several limitations. These included possible ascertainment bias due to reliance on an administrative claims database, exclusion of uninsured populations, lack of consistent follow-up, and absence of validated diagnostic codes for some diseases. Despite these, the authors noted that the E-values suggested reasonable robustness of the associations.
The study highlights that seborrheic dermatitis, beyond being a localized skin disorder, may serve as an indicator of systemic epithelial barrier dysfunction.
"The results reinforce the epithelial barrier theory and pave the way for further research to understand the molecular and physiological pathways linking these diseases. Future investigations may focus on the temporal relationship and underlying mechanisms connecting seborrheic dermatitis to other EBDs, potentially aiding in the development of integrated therapeutic strategies," the authors concluded.
Reference:
Meng S, Berna R, Hoffstad O, et al. Epithelial Barrier Diseases Among Adult Patients With Seborrheic Dermatitis. JAMA Dermatol. Published online November 05, 2025. doi:10.1001/jamadermatol.2025.4313
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