Vitamin D deficiency and atopic dermatitis severity in a Bangladeshi population living in East London: A cross-sectional study.

Background: Atopic eczema is a common, chronic, inflammatory skin condition with considerable heterogeneity. South Asian people living in the UK frequently have low serum vitamin D3 (25(OH)D ₃ ), and those with atopic disease can present with severe eczema. The association between vitamin D deficiency and eczema severity, and the role of vitamin D supplementation in atopic eczema is inconsistent, and under-researched in people with Asian ancestry.
Objectives: This cross-sectional study investigates the association between serum 25(OH)D ₃ and eczema severity in a cohort of South Asian children and young adults living in London.
Methods: Eligible participants were Bangladeshi children and young adults aged 0-30 years with eczema, living in London and participating in the Tower Hamlets Eczema Assessment study. Data was collected via parent/patient self-reporting, clinical history and examination, and hospital databases. 25(OH)D ₃ levels were documented retrospectively, if available, from hospital databases. Eczema severity was classified by Eczema Area and Severity Index (EASI) score less than or greater than 10 (clear-mild vs. moderate-severe). Multivariate logistic regression was used to adjust for confounding factors.
Results: 681 participants were included in analyses. 25(OH)D ₃ results were available for 49.6% (338/681), 84.3% of which had deficient or insufficient lowest 25(OH)D ₃ . Lowest 25(OH)D ₃ was inversely correlated with EASI score (Spearman's rank R ²  = -0.24, p  < 0.001). 26.1% (178/681) had EASI >10 and a lower median lowest and nearest 25(OH)D ₃ . After adjustment for confounding EASI > 10 was significantly associated with a lowest 25(OH)D ₃  < 25 (OR 3.21, 95%CI 1.35, 8.60), use of mild-moderate potency topical steroid on the face and neck (OR 3.11, 95%CI 1.86, 5.31), calcineurin inhibitor on the face and neck (OR 2.79, 95% CI 1.26, 6.10) and potent - very potent topical steroid on the face and neck (OR2.23, 95%CI 1.02, 4.77) and body (OR 2.11, 95%CI 1.18, 3.87).
Discussion: Vitamin D plays a role in modulation of proteins required for skin barrier function and regulation of the innate immune system, suggesting 25(OH)D ₃ deficiency contributes to skin inflammation. This study demonstrates a relationship between 25(OH)D ₃ deficiency and worse eczema severity in a cohort of South Asian children and young adults.
Competing Interests: Rebecca L. McCarthy: Position funded by Palvella Therapeutics to work on a clinical trial. Unrelated to this work and all funding goes to the university. Edel A. O'Toole: Research funding: Kamari Pharma, Unilever. Consultancy: Azitra Inc, Palvella Therapeutics and Kamari Pharma; Speaker: Almirall. All unrelated to this work and all funding goes to the university.
(© 2024 The Authors. Skin Health and Disease published by John Wiley & Sons Ltd on behalf of British Association of Dermatologists.)