title: Upper and lower airway patency are associated in young children.
abstract: BACKGROUND
  Although allergic rhinitis and asthma frequently coexist, the nature of this association is poorly understood. Therefore, we examined whether upper and lower airway patency are associated.
  
  
  METHODS
  We investigated 221 6-year-old children from the Copenhagen Prospective Study on Asthma in Childhood birth cohort, assessing upper airway patency by acoustic rhinometry before and after alpha-agonist, and lower airway patency by spirometry before and after beta2-agonist. Furthermore, we measured blood eosinophil count, nasal eosinophilia, total IgE, and fraction of exhaled nitric oxide. Associations were investigated by generalized linear models.
  
  
  RESULTS
  Decongested nasal airway patency and post-beta2 FEV(1) were significantly associated (P = .007). The association remained significant after adjustments for sex, body size, FVC, and atopic diseases (beta-coefficient 2.85 cm(3); 95% CI, 0.42 to 5.29; P = .02). Baseline values of upper and lower airway patency were also significantly associated (beta-coefficient 0.89 cm(3); 95% CI, 0.26-1.51; P = .01). In addition, blood eosinophil count and nasal eosinophilia were inversely associated with decongested nasal airway patency, beta-coefficient -0.42 cm(3) (95% CI, -0.77 to -0.07; P = .02) and beta-coefficient -0.47 cm(3) (95% CI, -0.89 to -0.05; P = .03), respectively.
  
  
  CONCLUSIONS
  We found a strong and consistent association between upper and lower airway patency. This may be due to a common pathology, as suggested by the inverse association between decongested nasal airway patency, blood eosinophil count, and nasal eosinophilia. Alternatively, the association between upper and lower airway patency might reflect a physiologic background for the common comorbidity.
authors.affiliation: Danish Pediatric Asthma Center, Copenhagen University Hospital, Gentofte, Denmark.
authors.forename: Bo Lund Krogsgaard
authors.initials: BL
authors.lastname: Chawes
authors.forename: Eskil
authors.initials: E
authors.lastname: Kreiner-Møller
authors.forename: Hans
authors.initials: H
authors.lastname: Bisgaard
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage; D000318:Adrenergic beta-Agonists / Q000008:administration & dosage; D000402:Airway Obstruction / Q000503:physiopathology*; D000886:Anthropometry; D001249:Asthma / Q000503:physiopathology*; D015415:Biomarkers / Q000032:analysis; D002648:Child; D004802:Eosinophilia / Q000175:diagnosis; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D007073:Immunoglobulin E / Q000032:analysis; D016014:Linear Models; D008297:Male; D009569:Nitric Oxide / Q000032:analysis; D011446:Prospective Studies; D006255:Rhinitis, Allergic, Seasonal / Q000503:physiopathology*; D023842:Rhinometry, Acoustic; D013147:Spirometry
chemical_list: D000316:Adrenergic alpha-Agonists; D000318:Adrenergic beta-Agonists; D015415:Biomarkers; D009569:Nitric Oxide; D007073:Immunoglobulin E