TOPLINE: 

In a US study of over 20 million patients, seborrheic dermatitis showed significant associations with multiple epithelial barrier diseases (EBDs), including various skin, gastrointestinal, and ocular conditions, supporting the epithelial barrier theory (EBT) model.

METHODOLOGY:

• The EBT proposes that barrier disruption can drive systemic immune dysregulation and chronic inflammatory diseases. In this retrospective cohort study, the researchers examined whether adults with seborrheic dermatitis have higher rates of other EBDs across skin, gastrointestinal, respiratory, and ocular systems.
• The researchers evaluated 20,274,189 adults with at least 1 year of continuous enrollment and a minimum of two visits to medical professionals on Optum's Clinformatics Data Mart Database, from January 2016 through June 2022.
• Of these, 733,776 patients had seborrheic dermatitis (median age, 62.63 years; 54.7% women), and 19,540,413 did not have seborrheic dermatitis (median age, 53.21 years; 54.47% women).
• The primary outcome was an EBDs diagnosis at any time during the observation period. The study focused on EBDs primarily presenting at the epithelial surface skin and respiratory, gastrointestinal, and ocular sites. The mean follow-up duration was 3.46 years, and total follow-up exceeded 70 million person-years.

TAKEAWAY:

• Seborrheic dermatitis showed strong associations with multiple dermatologic EBDs: Rosacea (odds ratio [OR], 4.52; P < .001), alopecia areata (OR, 4.02; P < .001), psoriasis (OR, 3.26; P < .001), atopic dermatitis (OR, 3.21; P < .001), contact dermatitis (OR, 2.25; P < .001), hidradenitis suppurativa (OR, 1.63; P < .001), bullous pemphigoid (OR, 1.60; P < .001), pemphigus vulgaris (OR, 1.48; P <.001), and chronic spontaneous urticaria (OR, 1.35; P < .001).
• Seborrheic dermatitis was also positively associated with various non-dermatologic EBDs, including rhinosinusitis (OR, 1.24; P < .001), celiac disease (OR, 1.36; P < .001), irritable bowel syndrome (OR, 1.32; P < .001), ocular allergy (OR, 1.39; P < .001), and dry eye (OR, 1.48; P < .001).
• Negative associations were found with EBDs and chronic obstructive pulmonary disease (OR, 0.72; P < .001) and pulmonary hypertension (OR, 0.70; P < .001).

IN PRACTICE:

"This retrospective cohort study found that seborrheic dermatitis, a common EBD of the skin, is associated with other EBDs that originate at various epithelial barriers, including skin, respiratory, gastrointestinal, and ocular surfaces," the authors concluded. "The results both support and encourage further evaluation of the EBT model in the pathogenesis of EBDs."

SOURCE:

The study was led by Sabrina Meng, BS, University of Pennsylvania, Philadelphia, and was published online on November 5 in JAMA Dermatology.

LIMITATIONS: 

Administrative claims data could miss uninsured populations; continuous enrollment requirements could reduce follow-up; and unmeasured confounding could be present.

DISCLOSURES:

The authors did not disclose any funding information. One author reported receiving grants and personal fees from Pfizer, Bristol Myers Squibb, and Incyte Consulting outside the submitted work. No other disclosures were reported.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.