Unique features of non-obstructive emphysema and pure airway obstruction

SETTING Emphysema without airway obstruction or airway obstruction without emphysema are often detected clinically, although they are commonly co-existent. We therefore tested the hypothesis that non-obstructive emphysema and pure airway obstruction have unique features. METHODS A case-control observation study was undertaken retrospectively in a patient cohort at a single centre. Among 2662 subjects who underwent chest computed tomography and pulmonary function tests, we enrolled 90 patients with non-obstructive emphysema, 119 with pure airway obstruction, 81 with obstructive emphysema and 2031 subjects as normal controls. The features of the four groups were analysed and compared. RESULTS Higher serum homocysteine (13.4 ± 7.4 vs. 11.6 ± 4.6 mol/l), higher rate of osteoporosis (15.8% vs. 4.5%), higher leukocyte count, higher male ratio, lower serum albumin and lower body mass index were observed in subjects with non-obstructive emphysema than in controls (P < 0.05). In multiple logistic regression analysis of groups without airway obstruction, osteoporosis, hyperhomocysteinaemia, hypoalbuminaemia and higher leukocyte count were independent factors associated with non-obstructive emphysema (P < 0.05). CONCLUSION Hyperhomocysteinaemia, hypoalbuminaemia, osteoporosis and higher leukocyte count were independent predictors of non-obstructive emphysema.