title: Impulse Oscillometry as a Predictor of Asthma Exacerbations in Young Children.
abstract: BACKGROUND
  In a post-hoc analysis of a pediatric asthma study, we identified the predictors of asthma exacerbations (AEs) and related them to forced expiratory volume (FEV1), the FEV1/FVC ratio, and bronchial hyperresponsiveness (BHR).
  
  
  OBJECTIVE
  We sought to detect predictors of AEs in a prospective study that utilizes impulse oscillometry (IOS) and to compare the results to previously determined predictors.
  
  
  METHODS
  A moderate AE was defined as an increased use of salbutamol during coughing episodes. Pulmonary function and BHR were measured during symptom- and medication-free periods. Additionally, allergen testing and IOS were included. To calculate the sensitivity and specificity of AE detection, a receiver-operating characteristic (ROC) curve was plotted, and accuracy was measured with the area under the ROC curve (AUC). A logistic regression analysis was used to predict the probability of an exacerbation.
  
  
  RESULTS
  Seventy-five pediatric patients (4-7 years of age) with intermittent asthma were included. In 69 patients, the following cut-off values demonstrated the best sensitivity and specificity combination for predicting an AE: FEV1 103.2% (AUC 0.62), BHR (PD20methacholine) 0.13 mg (AUC 0.61), and, in 54 children, Rrs5 0.78 kPa × l-1 × s (AUC 0.80). Logistic regression analysis demonstrated that the combination of all parameters predicted the individual risk of AEs with an accuracy of 86%.
  
  
  CONCLUSIONS
  IOS, a simple method, predicted the probability of AEs in young children. Airway resistance, measured by IOS, was superior to FEV1 and methacholine testing. The current data suggest that peripheral airway obstruction is present during symptom-free periods and that these children more likely experience AEs.
authors.affiliation: Department of Allergy, Pulmonology and Cystic Fibrosis, Children's Hospital, Goethe University, Frankfurt am Main, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Schulze
authors.forename: Silke
authors.initials: S
authors.lastname: Biedebach
authors.forename: Martin
authors.initials: M
authors.lastname: Christmann
authors.forename: Eva
authors.initials: E
authors.lastname: Herrmann
authors.forename: Sandra
authors.initials: S
authors.lastname: Voss
authors.forename: Stefan
authors.initials: S
authors.lastname: Zielen
mesh_terms: D001249:Asthma / Q000175:diagnosis*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D016015:Logistic Models; D008297:Male; D016210:Methacholine Chloride; D009991:Oscillometry; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012882:Skin Tests; D000067251:Symptom Flare Up; D014797:Vital Capacity
chemical_list: D016210:Methacholine Chloride