A longitudinal study by Parr et al of subjects with chronic bronchitis has demonstrated in a subgroup analysis that sputum MPO correlated with decline in FEV/ , sputum LTB4 with Dlco decline, and IL-8 with progression of lung densito-metric changes. In our study, no correlation of baseline inflammatory markers with progression of CT scan densitometry was observed. This difference from the study reported by Parr et al may reflect differences in patient phenotype or the number of subjects studied. However, in the current study there was a significant correlation between the change of sputum biomarker level and change in CT scan score for MPO and MCP-1 (e-Appendix 1, Figure 6). There was also a significant correlation between the baseline sputum mediator levels of either MPO or MCP-1 and change in volume-adjusted Dlco from baseline to year 4, as well as a correlation between the baseline sputum mediator level of MMP-9 and change in FEV1 from baseline to year 4 (e-Appendix 1, Fig 6 / .
The volume-adjusted Dlco correlated better than the non-volume-adjusted Dlco with the biomarkers measured (e-Appendix 1). The importance of using CT scans to phenotype subjects in studies of COPD-E and control subjects (such as current smokers without COPD-E) is the demonstration that, unlike the normal current smokers in this study, control “healthy” smoking subjects with near-normal FEV1 may have emphysematous lesions on CT scan and, thus, be misclassified if only pulmonary function studies and not CT scans are performed. Chest CT scans are providing an important method of documenting the extent of emphysema and have demonstrated canadian viagra online that the area of the lung with chest CT scan attenuation values below —910 HU and —950 HU correlates significantly with macroscopic and microscopic pathologic features of emphysema. Although there are many cross-sectional studies demonstrating the association of low attenuation on chest CT scan and emphysema, more recent longitudinal studies have investigated the progression of emphysema on chest CT scan over time periods ranging from 6 months to 5 years but have not examined longitudinal changes in levels of biomarkers of inflammation in relation to longitudinal changes in CT scans in ex-smokers.