Assessment of the Portable COPD-6 Device for Detecting Obstructive Airway Diseases

Objectives: To evaluate the agreement and the association with FEV1, FEV6 and FEV1/FEV6 measured with the Vitalograph-COPD-6 portable device and the FEV1, FVC and FEV1/FVC by conventional spirometry, and to analyse the validity of this device to detect obstruction. Methodology: 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 FEV1/FEV6 in detecting obstruction, and the sensitivity, specificity, predictive values (PPV and NPV), and probability ratios (PR+ and PR-) of the different FEV1/FEV6 cut-off points in the detection of obstruction. Results: The prevalence of obstruction was 47%. The kappa index was 0.59 when an FEV1/FEV6 < cut-off point of <0.7 was used. The ICC and the r between the FEV1 measured by the two instruments, FEV6 and FEV1/FEV6 measured by the Vitalograph-COPD-6 and the FVC and FEV1/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 FEV1/FEV6 (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 FEV1/FEV6 was obtained with cut-off points greater than 0.7. (C) 2010 SEPAR. Published by Elsevier Espana, S.L. All rights reserved.