title: The bronchodilator response as a predictor of inhaled corticosteroid responsiveness in asthmatic children with normal baseline spirometry.
abstract: BACKGROUND
  Although inhaled corticosteroids (ICS) are considered first line controller therapy in children with persistent asthma, heterogeneity of the ICS response can be an important clinical problem. The purpose of this study is to determine the value of the bronchodilator response (BDR) in identifying the ICS responder and establish the optimal BDR cut-point that could be particularly useful in the clinic setting when baseline spirometry is normal.
  
  
  METHODS
  Mexican American asthmatic children, 5-18 years, with normal baseline spirometry who required low dose (step 2), or medium dose (step 3) ICS therapy were evaluated by skin prick test for atopy, and pre- and post-bronchodilator spirometry. ICS responders were defined by a ≥7.5% improvement in the FEV1 following 4-6 weeks of therapy. The optimal cut-point was determined by Receiver Operator Characteristic (ROC) curves as the best balance between sensitivity and specificity.
  
  
  RESULTS
  There were 34.8% of the 132 study patients who were ICS responders. ROC curves showed the BDR ≥10% to be an optimal cut-point with sensitivity 46%, specificity 76%, positive predictive value (PPV) 50%, and negative predictive value (NPV) 72%. Atopic females with a BDR ≥10% had a PPV of 73%.
  
  
  CONCLUSIONS
  The composite phenotype of female gender, atopic, and the BDR of ≥10% identified 73% as ICS responders compared to 50% in our overall population with a BDR of ≥10% alone, with minimal false positives. We suggest that the BDR in conjunction with gender and atopic status be considered as potentially useful predictors of the ICS responder, particularly when baseline spirometry is normal.
authors.affiliation: Breathmobile, CHOC Children's Hospital, Orange County, Orange, California.
authors.forename: Stanley P
authors.initials: SP
authors.lastname: Galant
authors.forename: Tricia
authors.initials: T
authors.lastname: Morphew
authors.forename: Olga
authors.initials: O
authors.lastname: Guijon
authors.forename: Linh
authors.initials: L
authors.lastname: Pham
mesh_terms: D000280:Administration, Inhalation; D000293:Adolescent; D001249:Asthma / Q000188:drug therapy*; D001993:Bronchodilator Agents / Q000008:administration & dosage*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005541:Forced Expiratory Volume; D005938:Glucocorticoids / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D012372:ROC Curve; D012680:Sensitivity and Specificity; D012737:Sex Factors; D013147:Spirometry
chemical_list: D001993:Bronchodilator Agents; D005938:Glucocorticoids
keywords: atopy; biomarkers; gender; hispanic; phenotypes