title: Clinical data discriminating between adults with positive and negative results on bronchodilator testing.
abstract: OBJECTIVE
  To evaluate how spirometry, symptoms and smoking discriminate between subjects who are responsive to bronchodilator testing and those who are non-responsive, and to examine how cut-off points of positive tests are related to symptoms of chronic obstructive pulmonary disease (COPD) and asthma.
  
  
  METHODS
  Subjects aged 47-48 and 71-73 years living in Bergen, Norway, were recruited. The 3506 participants (69%) filled in questionnaires and performed a bronchodilator test using salbutamol.
  
  
  RESULTS
  Tests were positive (forced expiratory volume in 1 s [Delta FEV1] >or=200 ml and >or=12%) in 107 subjects (3%). In logistic regression, spirometry (FEV1 < 80%, OR 6.0, 95%CI 3.6-10.2, and FEV1/FVC < 0.70, OR 3.1, 95%CI 1.9-5.2) and pack-years >or= 20 (OR 0.3, 95%CI 0.2-0.7), but not symptoms, predicted the test outcome. FEV1% and FEV1/forced volume capacity (FVC) discriminated equally well between positive and negative tests (area under the receiver operating characteristic [ROC] curve 0.81, 95%CI 0.77-0.85 vs. 0.77, 95%CI 0.72-0.82). The largest likelihood ratio for positive tests was 5.4 (95%CI 3.8-7.8) using FEV1 < 80% and FEV1/FVC < 0.70.
  
  
  CONCLUSIONS
  Spirometry and to a lesser extent smoking, but not symptoms, are useful in discriminating between middle-aged and elderly patients with positive and negative bronchodilator tests. Acute responses to salbutamol, expressed by commonly used Delta FEV1 cut-off points, are poorly related to COPD- and asthma-like symptoms.
authors.affiliation: Section for Thoracic Medicine, Institute of Medicine, University of Bergen, Bergen, Norway. sverre.lehmann@helse-bergen.no
authors.forename: S
authors.initials: S
authors.lastname: Lehmann
authors.forename: P S
authors.initials: PS
authors.lastname: Bakke
authors.forename: G E
authors.initials: GE
authors.lastname: Eide
authors.forename: A
authors.initials: A
authors.lastname: Gulsvik
mesh_terms: D000328:Adult; D000368:Aged; D001249:Asthma / Q000175:diagnosis*; D001985:Bronchial Provocation Tests; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D016015:Logistic Models; D008297:Male; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis*; D012372:ROC Curve; D012680:Sensitivity and Specificity; D013147:Spirometry; D014797:Vital Capacity