The extent of emphysema in patients with COPD

BACKGROUND AND AIMS: The global initiative for COPD (GOLD) adopted the degree of airway obstruction as a measure of the severity of the disease. The objective of this study was to apply CT to assess the extent of emphysema in patients with chronic obstructive pulmonary disease (COPD) and relate this extent to the GOLD stage of airway obstruction.

MATERIALS AND METHODS: We included 209 patients with COPD. COPD was defined as FEV(1)/FVC < 0.70 and no reversibility to beta(2)-agonists. All patients were current smokers with a smoking history of >or=20 pack-years. Patients were assessed by lung function measurement and visual and quantitative assessment of CT, from which the relative area of emphysema below -910 Hounsfield units (RA-910) was extracted.

RESULTS: Mean RA-910 was 7.4% (n = 5) in patients with GOLD stage I, 17.0% (n = 119) in stage II, 24.2% (n = 79) in stage III and 33.9% (n = 6) in stage IV. Regression analysis showed a change in RA-910 of 7.8% with increasing severity according to GOLD stage (P < 0.001). Combined visual and quantitative assessment of CT showed that 184 patients had radiological evidence of emphysema, whereas 25 patients had no emphysema.

CONCLUSION: The extent of emphysema increases with increasing severity of COPD and most patients with COPD have emphysema. Tissue destruction by emphysema is therefore an important determinant of disease severity in COPD.