title: Vitamin D deficiency and its impact on asthma severity in asthmatic children.
abstract: BACKGROUND
  Despite obtaining evidences on association between vitamin D and development of lung in fetus, little is known about vitamin D level and its impact on severity of asthma in children. The present study aimed to assess the relationship between the asthma severity and vitamin D deficiency in asthmatic children.
  
  
  METHODS
  This case-control study was conducted on 106 individuals including asthmatic (n = 53) and healthy children (n = 53) who referred to Mofid hospital in Tehran in 2013. The level of serum vitamin D in both groups was measured by radioimmunoassay method at the reference lab and was categorized as sufficient (> 30 ng/ml), insufficient (20 to 30 ng/ml), or deficient (< 20 ng/ml). The control status of asthma in patients group was classified as controlled, partially controlled, and uncontrolled.
  
  
  RESULTS
  In the groups with and without asthma, the prevalence of vitamin D deficiency was 73.6 and 49.1%, and the prevalence of vitamin D insufficiency was 18.9 and 18.9%, while normal vitamin D level was revealed in 7.5 and 32.1%, respectively with a significant difference (p = 0.005). Using the multivariate logistic regression analysis, the presence of asthma was associated with reduced level of vitamin D (OR = 1.068, 95% CI: 1.027-1.110, P = 0.001). In this context, the risk for asthma in the children with vitamin D deficiency was 6.3 times of those with normal vitamin D level. Although the presence of asthma was strongly associated with reduced level of vitamin D in serum, neither severity of asthma nor control status of asthma were associated with vitamin D deficiency.
  
  
  CONCLUSIONS
  The presence of vitamin D deficiency effectively predict increased risk for childhood asthma; however the severity or control status of this event may not be predicted by confirming vitamin D deficiency.
authors.affiliation: Pediatric Nephrology Research Center, Faculty of Medicine, Mofid Children's Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Nasrin
authors.initials: N
authors.lastname: Esfandiar
authors.affiliation: Department of Pediatrics Cardiology, Faculty of Medicine, Mofid Children's Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Fariba
authors.initials: F
authors.lastname: Alaei
authors.affiliation: Department of Emergency Medicine, Faculty of Medicine, Mofid Children's Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Shahrzad
authors.initials: S
authors.lastname: Fallah
authors.affiliation: Allergy and Clinical Immunology Department, Mofid Children's Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran. delara77@yahoo.com.
authors.forename: Delara
authors.initials: D
authors.lastname: Babaie
authors.affiliation: Pediatric Nephrology Research Center, Faculty of Medicine, Mofid Children's Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Niloofar
authors.initials: N
authors.lastname: Sedghi
mesh_terms: D001249:Asthma / Q000150:complications*; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007492:Iran; D008297:Male; D012307:Risk Factors; D012720:Severity of Illness Index; D014808:Vitamin D Deficiency / Q000150:complications*
keywords: Asthma; Children; Risk; Vitamin D