title: [Assessment of the portable COPD-6 device for detecting obstructive airway diseases].
abstract: OBJECTIVE
  To evaluate the agreement and the association with FEV(1), FEV(6) and FEV(1)/FEV(6) measured with the Vitalograph-COPD-6 portable device and the FEV(1), FVC and FEV(1)/FVC by conventional spirometry, and to analyse the validity of this device to detect obstruction.
  
  
  METHODS
  A cross-sectional, descriptive, prospective study, that included 180 subjects. A conventional spirometry and one with the Vitalograph-COPD-6 were sequentially performed on them. The agreement was analysed [kappa index and interclass correlation coefficient (ICC)], as well as the association [Pearson correlation coefficient (r)], area under the ROC curve (AUC) of the FEV(1)/FEV(6) in detecting obstruction, and the sensitivity, specificity, predictive values (PPV and NPV), and probability ratios (PR+ and PR-) of the different FEV(1)/FEV(6) cut-off points in the detection of obstruction.
  
  
  RESULTS
  The prevalence of obstruction was 47%. The kappa index was 0.59 when an FEV(1)/FEV(6) < cut-off point of <0.7 was used. The ICC and the r between the FEV(1) measured by the two instruments, FEV(6) and FEV(1)/FEV(6) measured by the Vitalograph-COPD-6 and the FVC and FEV(1)/FVC determined by the spirometer were all greater than 0.92. The ROC AUC was 0.97. To detect obstruction, if the cut-off point of FEV(1)/FEV(6) (for COPD-6) was <0.70, the sensitivity, specificity, PPV, NPV, CR+ and CR- were, 58%, 100%, 100%, 73%, infinity and 0.42, respectively. For a cut-off point of <0.8, they were 96%, 76%, 78%, 96%, 3.8 and 0.05, respectively.
  
  
  CONCLUSIONS
  The portable Vitalograph-COPD6 device is precise for the detection of airway obstruction. The best sensitivity/specificity of FEV(1)/FEV(6) was obtained with cut-off points greater than 0.7.
authors.affiliation: Grupo de Investigación en Enfermedades Respiratorias e Infecciosas, Complejo Hospitalario Universitario de Vigo, Vigo, España.
authors.forename: Cristina
authors.initials: C
authors.lastname: Represas Represas
authors.forename: Maribel
authors.initials: M
authors.lastname: Botana Rial
authors.forename: Virginia
authors.initials: V
authors.lastname: Leiro Fernández
authors.forename: Ana Isabel
authors.initials: AI
authors.lastname: González Silva
authors.forename: Víctor
authors.initials: V
authors.lastname: del Campo Pérez
authors.forename: Alberto
authors.initials: A
authors.lastname: Fernández-Villar
mesh_terms: D003430:Cross-Sectional Studies; D004867:Equipment Design; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008173:Lung Diseases, Obstructive / Q000175:diagnosis* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012129:Respiratory Function Tests / Q000295:instrumentation; D012680:Sensitivity and Specificity; D013147:Spirometry