Association between markers of emphysema and more severe chronic obstructive pulmonary disease.

Background: The predominant emphysema phenotype is associated with more severe airflow limitation in
patients with chronic obstructive pulmonary disease (COPD). A study was undertaken to investigate
whether COPD patients, with or without emphysema quantitatively confirmed by high resolution computed
tomography (HRCT), have different COPD severity as assessed by the BODE index (body mass index,
airflow obstruction, dyspnoea, exercise performance) and inspiratory capacity to total lung capacity ratio
(IC/TLC), and by different biological markers of lung parenchymal destruction.
Methods: Twenty six outpatients with COPD and eight healthy non-smokers were examined. Each subject
underwent HRCT scanning, pulmonary function tests, cell counts, and measurements of neutrophil elastase,
matrix metalloproteinase (MMP)-9 and tissue inhibitor of metalloproteinase (TIMP)-1 in induced sputum, as
well as measurement of desmosine, a marker of elastin degradation in urine, plasma and sputum.
Results: Patients with HRCT confirmed emphysema had a higher BODE index and lower IC/TLC ratio than
subjects without HRCT confirmed emphysema and controls. Forced expiratory volume in 1 second (FEV1),
FEV1/forced vital capacity ratio, and carbon monoxide transfer coefficient were lower, whereas the
number of eosinophils, MMP-9, and the MMP-9/TIMP-1 ratio in sputum were higher in patients with
emphysema. In COPD patients the number of sputum eosinophils was the biological variable that
correlated positively with the HRCT score of emphysema (p = 0.04).
Conclusions: These results suggest that COPD associated with HRCT confirmed emphysema is
characterised by more severe lung function impairment, more intense airway inflammation and, possibly,
more serious systemic dysfunction than COPD not associated with HRCT confirmed emphysema.