title: Vitamin D levels and status amongst asthmatic and non-asthmatic adolescents in Cyprus: a comparative cross-sectional study.
abstract: BACKGROUND
  Emerging evidence suggests that vitamin D might be implicated in asthma pathophysiology. This study aims to compare Vitamin D mean serum levels and status between asthmatic and non-asthmatic adolescents and investigate the association of vitamin D with asthma severity.
  
  
  METHODS
  In a cohort of adolescents aged 16-17 years, those reporting wheezing in the past 12 months and Ever asthma on the ISAAC questionnaire were invited to participate and formed the Active Asthmatics group. Controls were selected amongst Never Wheezers/Never Asthmatics (NWNA). Differences in mean 25(OH)D serum levels and vitamin D status between AA and NWNA were examined in multivariate linear and logistic regression models respectively, adjusting for potential confounders. Within AA, differences in vitamin D levels were assessed across asthma severity indicators.
  
  
  RESULTS
  A total of 69 AA and 671 NWNA participated in the study. Unadjusted mean 25(OH)D serum levels were 22.90 (SD 6.41), and 21.15 (SD 5.59) ng/mL in NWNA and AA respectively (p = 0.03). In adjusted models, mean 25(OH)D levels remained significantly lower amongst AA compared to NWNA (adjusted beta coefficient -1.68, 95% CI -3.24, -0.13). Severe (<12 ng/mL), moderate (<25 ng/mL) or insufficient (<30 ng/mL) vitamin D status was more prevalent among AA who were 1.6 times (95% CI 1.01, 2.53) more likely to belong to a lower vitamin D category compared to NWNA. Within AA, there was a negative trend between vitamin D levels and the number of reported asthma severity indicators.
  
  
  CONCLUSIONS
  Levels of vitamin D tend to be lower among asthmatic compared to non-asthmatic children and in those with severe asthma independent of important confounders.
authors: Cyprus International Institute for Environmental & Public Health in association with Harvard School of Public Health, Cyprus University of Technology, Limassol, Cyprus. kolokotroni.o@unic.ac.cy.|Department of Nursing, School of Health Sciences, Cyprus University of Technology, Limassol, Cyprus. kolokotroni.o@unic.ac.cy.|St George University of London Medical Programme at the University of Nicosia Medical School, Nicosia, Cyprus. kolokotroni.o@unic.ac.cy.
authors: Ourania
authors: O
authors: Kolokotroni
authors: 3rd Department of Pediatrics, Attikon University Hospital, University of Athens Medical School, Athens, Greece. anpapado@med.uoa.gr.
authors: Anna
authors: A
authors: Papadopoulou
authors: Department of Nursing, School of Health Sciences, Cyprus University of Technology, Limassol, Cyprus. nicos.middleton@cut.ac.cy.
authors: Nicos
authors: N
authors: Middleton
authors: Department of Nursing, School of Health Sciences, Cyprus University of Technology, Limassol, Cyprus. christiana.kouta@cut.ac.cy.
authors: Christiana
authors: C
authors: Kouta
authors: Department of Nursing, School of Health Sciences, Cyprus University of Technology, Limassol, Cyprus. vasilios.raftopoulos@cut.ac.cy.
authors: Vasilios
authors: V
authors: Raftopoulos
authors: 3rd Department of Pediatrics, Attikon University Hospital, University of Athens Medical School, Athens, Greece. pnikolaidou@med.uoa.gr.
authors: Polyxeni
authors: P
authors: Nicolaidou
authors: Cyprus International Institute for Environmental & Public Health in association with Harvard School of Public Health, Cyprus University of Technology, Limassol, Cyprus. p.yiallouros@cut.ac.cy.
authors: Panayiotis K
authors: PK
authors: Yiallouros
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000097:blood / Q000453:epidemiology*; D015897:Comorbidity; D003430:Cross-Sectional Studies; D003535:Cyprus / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D015995:Prevalence; D011795:Surveys and Questionnaires; D014807:Vitamin D / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology*; D014815:Vitamins / Q000097:blood
chemical_list: D014815:Vitamins; D014807:Vitamin D
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