title: Corticosteroid use and bone mineral accretion in children with asthma: effect modification by vitamin D.
abstract: BACKGROUND
  The adverse effects of corticosteroids on bone mineral accretion (BMA) have been well documented. Vitamin D insufficiency, a prevalent condition in the pediatric population, has also been associated with decreased bone mineral density (BMD).
  
  
  OBJECTIVE
  We sought to determine whether children with asthma who have lower vitamin D levels are more susceptible to the negative effects of corticosteroids on BMD over time.
  
  
  METHODS
  Children aged 5 to 12 years with mild-to-moderate asthma who participated in the Childhood Asthma Management Program were followed for a mean of 4.3 years. Total doses of inhaled corticosteroids and oral corticosteroids (OCSs) were recorded, serum 25-hydroxyvitamin D3 levels were measured at the beginning of the trial, and serial dual-energy x-ray absorptiometry scans of the lumbar spine were performed. Annual BMA rates were defined as follows: [(BMD at 4 years' follow-up - BMD at baseline)/4 years].
  
  
  RESULTS
  BMA was calculated for 780 subjects. In boys baseline vitamin D levels significantly modified the relationship between OCSs and BMA (vitamin D × OCS interaction, P= .023). Stratification by vitamin D levels showed a decrease in BMA with increased use of OCSs in vitamin D-insufficient boys only (P< .001). Compared with vitamin D-sufficient boys, vitamin D-insufficient boys exposed to more than 2 courses of OCSs per year had twice the decrease in BMA rate (relative to boys who were OCS unexposed).
  
  
  CONCLUSIONS
  Vitamin D levels significantly modified the effect of OCSs on BMA in boys. Further research is needed to examine whether vitamin D supplementation in children with poorly controlled asthma might confer benefits to bone health.
authors.affiliation: Channing Laboratory, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA. reszt@channing.harvard.edu
authors.forename: Sze Man
authors.initials: SM
authors.lastname: Tse
authors.forename: H William
authors.initials: HW
authors.lastname: Kelly
authors.forename: Augusto A
authors.initials: AA
authors.lastname: Litonjua
authors.forename: Mark L
authors.initials: ML
authors.lastname: Van Natta
authors.forename: Scott T
authors.initials: ST
authors.lastname: Weiss
authors.forename: Kelan G
authors.initials: KG
authors.lastname: Tantisira
mesh_terms: D000305:Adrenal Cortex Hormones / Q000009:adverse effects / Q000627:therapeutic use*; D018927:Anti-Asthmatic Agents / Q000627:therapeutic use*; D001249:Asthma / Q000188:drug therapy*; D015519:Bone Density / Q000187:drug effects; D019819:Budesonide / Q000627:therapeutic use; D002112:Calcifediol / Q000494:pharmacology; D002113:Calcification, Physiologic / Q000187:drug effects*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D017835:Nedocromil / Q000627:therapeutic use; D016896:Treatment Outcome; D014807:Vitamin D / Q000097:blood / Q000494:pharmacology*
chemical_list: D000305:Adrenal Cortex Hormones; D018927:Anti-Asthmatic Agents; D017835:Nedocromil; D014807:Vitamin D; D019819:Budesonide; D002112:Calcifediol