title: The potential use of spirometry during methacholine challenge test in young children with respiratory symptoms.
abstract: BACKGROUND
  The concentration of methacholine that causes a fall of 20% from baseline forced expiratory volume in the first second (PC20-FEV1) in the methacholine challenge test (MCT) is not usually considered a diagnostic tool in preschool children since PC20-FEV1 may not be achievable <6 years of age.
  
  
  OBJECTIVE
  To assess the usefulness of various spirometry indices obtained during MCT in a large group of 3- to 6-year-old children with respect to their clinical diagnosis.
  
  
  METHODS
  Standardized MCT (inhaled triple-concentration increments [0.057-13.925 mg] of methacholine solution) was performed by 84 children previously diagnosed with asthma (asthmatics) and 48 with prolonged cough (coughers). Spirometry was determined at baseline and between inhalations; PC20-FEV1 and PC25-FEV0.5 were calculated.
  
  
  RESULTS
  PC20-FEV1 values were significantly less in the asthmatics than in the coughers (mean +/- SD was 3.21 +/- 4.32 vs. 22.35 +/- 3.66 ml/mg). Similarly, PC25-FEV0.5 was 1.48 +/- 3.08 in the asthmatics and 9.45 +/- 12.59 mg/ml/Mch in the coughers, P < 0.0001. A cut-off at 4.0 mg/ml for PC20-FEV1 had 77.4% sensitivity and 75.0% specificity, a cut-off at 2.2 mg/ml for PC25-FEV0.5 had 73.8% sensitivity and 72.9% specificity, for clinical diagnosis of asthma. PC25-FEV0.5 also showed a correlation with age.
  
  
  CONCLUSIONS
  Our findings suggest that MCT can be performed in preschool children with various respiratory symptoms. PC25-FEV0.5 may be a better end-point parameter. Children with a clinical diagnosis of asthma respond to a lower MCT concentration than children with cough. Further studies are needed to determine airway responsiveness in healthy young children and to further assess the contribution of MCT to the clinical diagnosis in this age group.
authors.affiliation: Pediatric Pulmonary Unit, Meyer Children's Hospital, Rambam Medical Center, Technion-Israel Institute of Technology, Haifa 31096, Israel. avi_vil@bezeqint.net
authors.forename: Daphna
authors.initials: D
authors.lastname: Vilozni
authors.forename: Galit
authors.initials: G
authors.lastname: Livnat
authors.forename: Husein
authors.initials: H
authors.lastname: Dabbah
authors.forename: Nael
authors.initials: N
authors.lastname: Elias
authors.forename: Fahed
authors.initials: F
authors.lastname: Hakim
authors.forename: Lea
authors.initials: L
authors.lastname: Bentur
mesh_terms: D001249:Asthma / Q000175:diagnosis*; D001985:Bronchial Provocation Tests / Q000379:methods*; D016085:Bronchoconstrictor Agents; D002648:Child; D002675:Child, Preschool; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D016210:Methacholine Chloride; D012372:ROC Curve; D013147:Spirometry
chemical_list: D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride