[Characteristics of chronic obstructive pulmonary disease phenotypes based on high-resolution CT and the relationship with interleukin-6].

OBJECTIVE: To classify the high-resolution CT (HRCT) phenotypes of COPD, and to investigate the clinical characteristics of various phenotypes and the relationship with airway inflammation. METHODS: Chest HRCT and pulmonary function tests were performed in 84 COPD patients. The patients were classified into 3 phenotypes according to the visual HRCT findings. Exhaled breath condensate was gathered from 30 patients and the interleukin (IL)-6 level was measured by ELISA. RESULTS: The COPD patients were classified into 3 phenotypes: Phenotype A, absence of emphysema, with or without bronchial wall thickening (n = 34); Phenotype E, emphysema without bronchial wall thickening (n = 23); and Phenotype M, emphysema with bronchial wall thickening (n = 27). The 3 phenotypes of COPD showed different characteristics in several aspects. Patients with phenotype A showed a higher body mass index [(25.1 +/- 4.4) kg/m(2) vs phenotype E (22.5 +/- 4.1) kg/m(2) and phenotype M (21.3 +/- 3.4) kg/m(2), F = 6.732, P < 0.01]. The prevalence of patients with milder dyspnea was lower in phenotype A compared with others (15/34) vs phenotype E (2/23) and phenotype M (6/27), chi(2) = 9.097, P < 0.05. The patients who complained of severe expectoration in phenotype E were fewer than those in other groups (0/23) vs phenotype A (2/34) and phenotype M (4/27), chi(2) = 8.702, P < 0.05. The FEV(1)/FVC and FEV(1)% in phenotype M [(53 +/- 14)% and (51 +/- 25)%] were significantly lower as compared with those in other phenotypes [(67 +/- 11)% and (72 +/- 24)% in phenotype A, and (53 +/- 14)% and (52 +/- 26)% in phenotype E], F = 10.252, F = 6.508, P < 0.01. The ratio of inspiratory capacity to total lung capacity (IC/TLC) in phenotype A was higher [phenotype A (41 +/- 17)%, phenotype E (33 +/- 13)%, phenotype M (28 +/- 13)%, F = 5.964, P < 0.01], while the ratio of residual volume to total lung capacity (RV/TLC) was lower [phenotype A (37 +/- 9)%, phenotype E (44 +/- 10)%, phenotype M (45 +/- 8)%, F = 6.954, P < 0.01]. Patients with different phenotypes showed various levels of IL-6 in exhaled breath condensate [phenotype A (19.9 +/- 6.3) ng/L, phenotype E (16.7 +/- 2.1) ng/L, phenotype M (25.6 +/- 4.4) ng/L, F = 7.749, P < 0.01]. CONCLUSION: Various morphological phenotypes of COPD based on HRCT showed different clinical characteristics and airway inflammation.