Evaluation of emphysema in patients with reversible airway obstruction using high-resolution CT

This study was carried out to determine whether asthma affects the development of emphysema.

We studied 62 patients with reversible airway obstruction during remission, and evaluated the presence and severity of emphysema using high-resolution CT. The emphysema score (ES) was evaluated with the visual scoring method on CT scans.

Of the 62 patients, 14 were judged to have emphysema. Patients with emphysema were significantly older and more likely to be male than those without emphysema. All patients with emphysema were smokers. There was no significant difference in the duration or severity of asthma between patients with and without emphysema. The 62 patients were divided into three groups according to the ES: 48 patients without emphysema (ES = 0%), 8 patients with mild emphysema (0% < ES < 15%), and 6 patients with more severe emphysema (ES > or = 15%). Highly significant differences between patients without emphysema and those with more severe emphysema were found in FEV1 (p<0.01), FEV1/FVC (p<0.001), diffusing capacity for carbon monoxide (DCO) (p<0.01), and DCO/alveolar volume (p<0.0001).

Neither the duration nor the severity of asthma was correlated with the presence of emphysema, while smoking history, sex, and age were strongly correlated. No patients with emphysema were found among the nonsmokers, including those with severe asthma or asthma of long duration. These results suggest that asthma does not lead to emphysema.