title: Vitamin D deficiency is associated with diagnosis and severity of childhood atopic dermatitis.
abstract: BACKGROUND
  Recent studies implicated the importance of vitamin D in innate immune defense and pathogenesis of allergic diseases. However, the impact of vitamin D deficiency on atopic dermatitis (AD) diagnosis and severity remains unclear. This case-control study investigated such relationship in Hong Kong Chinese children.
  
  
  METHODS
  Serum 25-hydroxyvitamin D [25(OH)D] levels of 498 AD children and 328 non-allergic controls were measured by immunoassay. Subjects were categorized into deficient (< 25 nm), insufficient (25-49.9 nm), and sufficient (≥ 50 nm) groups. Short-term and long-term AD severity was evaluated by physician-diagnosed SCORing Atopic Dermatitis (SCORAD) and Nottingham Eczema Severity Score (NESS), respectively. Atopy biomarkers were also measured for analysis.
  
  
  RESULTS
  The mean (s.d.) serum 25(OH)D levels in AD patients and controls were 28.9 (15.3) and 34.2 (14.5) nm, respectively (p < 0.001). More patients had serum 25(OH)D levels <25 nm than controls (47.8% vs. 26.6%). AD severity as indicated by both SCORAD and NESS showed inverse associations with serum 25(OH)D levels (respective p = 3.6 × 10(-4) and 0.004 when adjusted for age, sex, month of assessment, and immunoassay batch as covariates). Vitamin D-deficient patients (3.08 ± 0.76) had higher logarithm-transformed total IgE than those with insufficient (2.74 ± 0.69) and sufficient (2.72 ± 0.72) serum 25(OH)D levels (p < 0.001). The proportion of subjects with elevated IgE was higher in vitamin D-deficient (43.2%) than vitamin D-sufficient (20.0%) groups.
  
  
  CONCLUSIONS
  Vitamin D deficiency and insufficiency are prevalent in Hong Kong Chinese children. Vitamin D deficiency is associated with childhood AD and high total IgE. Serum 25(OH)D levels correlate inversely with both long- and short-term AD severity.
authors.affiliation: Department of Pediatrics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong.
authors.forename: Susan Shuxin
authors.initials: SS
authors.lastname: Wang
authors.forename: Kam Lun
authors.initials: KL
authors.lastname: Hon
authors.forename: Alice Pik-shan
authors.initials: AP
authors.lastname: Kong
authors.forename: Henry Nga-hin
authors.initials: HN
authors.lastname: Pong
authors.forename: Gary Wing-kin
authors.initials: GW
authors.lastname: Wong
authors.forename: Ting Fan
authors.initials: TF
authors.lastname: Leung
mesh_terms: D000293:Adolescent; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D002648:Child; D002681:China; D003876:Dermatitis, Atopic / Q000453:epidemiology* / Q000276:immunology; D018450:Disease Progression; D004804:Eosinophils / Q000276:immunology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007113:Immunity, Innate; D007073:Immunoglobulin E / Q000097:blood; D008297:Male; D013997:Time Factors; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000453:epidemiology* / Q000276:immunology
chemical_list: D015415:Biomarkers; D014807:Vitamin D; D007073:Immunoglobulin E; C104450:25-hydroxyvitamin D
keywords: atopic dermatitis; atopy; children; eczema; severity; vitamin D