Table 1.
Characteristics of study population (qRT-PCR study)
| Never-smokers | Smokers without COPD | COPD GOLD II | COPD GOLD III–IV | |
|---|---|---|---|---|
| Number | 18 | 26 | 34 | 14 |
| Gender ratio (male/female) | 6/12# | 19/7# | 31/3# | 8/6# |
| Age (years) | 65 (56–70) | 63 (55–70) | 66 (58–69)§ | 56 (54–60)*,§,‡ |
| Current smoker/ex-smoker | – | 16/10 | 22/12 | 0/14 |
| Smoking history (PY) | 0 (0–0) | 28 (15–45)* | 45 (40–60)*,§ | 30 (25–30)*,‡ |
| FEV1 post-BD (L) | 2.7 (2.3–3.2) | 2.7 (2.3–3.3) | 2.0 (1.8–2.4)*,§ | 0.7 (0.7–0.9)*,§,‡ |
| FEV1 post-BD (% predicted) | 102 (92–116) | 95 (93–112) | 68 (61–75)*,§ | 26 (20–32)*,§,‡ |
| FEV1/FVC post-BD (%) | 78 (75–83) | 75 (71–79)* | 56 (53–60)*,§ | 32 (27–35)*,§,‡ |
| DCO (% predicted) | 90 (80–105) | 80 (61–102) | 67 (51–87)* | 35 (33–41)*,§,‡ |
| KLCO (% predicted) | 103 (88–123) | 91 (68–107)* | 87 (62–108)* | 59 (50–65)*,§,‡ |
| ICS (yes/no) | 0/18# | 1/25# | 15/19# | 13/1# |
Notes: n=92. Data are presented as median (IQR). Mann–Whitney U-test:
*
p<0.05 versus never-smokers;
§
p<0.05 versus smokers without COPD;
‡
p<0.05 versus COPD GOLD II. Fisher’s exact test:
#
p<0.001. ‘–’ indicates not applicable.
Abbreviations: COPD, chronic obstructive pulmonary disease; DLCO, diffusing capacity of the lung for carbon monoxide; FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; GOLD, Global Initiative for Chronic Obstructive Lung Disease; ICS, inhaled corticosteroids; IQR, interquartile range; KCO, the ratio of DLCO to alveolar volume; post-BD, post-bronchodilator; PY, pack years; qRT-PCR, quantitative real-time polymerase chain reaction.