2009 Volume 48 Issue 7 Pages 513-521
Objective The concept of "lung age" is thought to be useful for understanding pulmonary function. In this study, we validated "lung age" to detect pulmonary function abnormalities in pulmonary diseases.
Methods We used both spirometry and an electronic FEV1/FEV6 meter (FEV6 meter) to perform pulmonary function tests. We evaluated the sensitivity and specificity of FEV6 and FEV1/FEV6, and calculated "lung age" in Japanese subjects including those with chronic obstructive pulmonary disease (COPD), bronchial asthma (BA), and interstitial lung diseases (ILD).
Results FEV1 (spirometer) vs. FEV1 (FEV6 meter), FVC (spirometer) vs. FEV6 (FEV6 meter), and FEV1/FVC (spirometer) vs. FEV1/FEV6 (FEV6 meter) measurements were all significantly and closely correlated. For the difference of "lung age" and "actual age", the area under the receiver operating characteristic curve (ROC-AUC) for detecting obstructive impairment was 0.807 (spirometer) and 0.772 (FEV6 meter), respectively. The corresponding ROC-AUC for detecting restrictive impairment was 0.891 and 0.836, respectively, and that for detecting both obstructive and restrictive impairment was 0.918 and 0.853, respectively. For detection of both obstructive and restrictive impairment, the difference of the "lung age" and "actual age" cut-off value, corresponding to the greatest sum of sensitivity and specificity, was 18.3 years (spirometer) and 19.8 years (FEV6 meter), respectively. The sensitivity was 0.783 (spirometer) and 0.801 (FEV6 meter), and the specificity was 0.895 (spirometer) and 0.790 (FEV6 meter), respectively.
Conclusion "Lung age" can provide an easy interpretation of the results, and can detect pulmonary function abnormalities in pulmonary diseases.
