Table 1. Demographic characteristics of individuals included in the association study at baseline.
| Variable | COPD patients (n = 142) | Smoking controls (n = 77) | Nonsmoking controls (n = 459) | p-value |
|---|---|---|---|---|
| Gender (% male) | 74 | 50 | 63 | <0.0001 |
| Age (years)* | 63 ± 10 | 48 ± 10 | 50 ± 9 | <0.0001 |
| Smoking history (pack-yrs)†* | 64 ± 28 | 35 ± 14 | 0 | <0.0001 |
| FEV1 (L)* | 1.50 ± 0.7 | 3 ± 0.7 | __ | NA |
| FEV1 (% pred)* | 56 ± 20 | 101 ± 14 | __ | NA |
| FVC (%)* | 86 ± 22 | 107 ± 15 | __ | NA |
| FEV1/FVC* | 51 ± 12 | 78 ± 7 | __ | NA |
| PaO2 (mmHg)* | 69.3 ± 13.5 | __ | __ | NA |
| IC/TLC (%) | 34 ± 12 | __ | __ | NA |
| KCO | 58 ± 7 | __ | __ | NA |
| 6MWD (m)* | 489 ± 89 | __ | __ | NA |
| BMI (Kg/m2) * | 28 ± 6 | __ | __ | NA |
| mMRC dysnea** | 1 (0–2) | __ | __ | NA |
| BODE index** | 2 (0–3) | __ | __ | NA |
| BODE index ≤ 2‡ | 103 | __ | __ | NA |
| BODE index > 2‡ | 46 | __ | __ | NA |
| GOLD index I-II‡ | 106 | __ | __ | NA |
| GOLD index III-IV‡ | 83 | __ | __ | NA |
* Data are presented as mean ± SD.
** Data are presented as median (P25-75).
† Number of packs of cigarettes smoked per day x number of years smoking.
‡ Number of subjects in the two groups of GOLD and BODE index considered to analysis.
Median was used as cutoff in the BODE index. FEV1: forced expiratory volume in one second; FVC: forced expiratory volume; % pred: predicted percentage; 6MWD: six-min walk distance test; BMI: body mass index; IC: inspiratory capacity, TLC: total lung capacity; PaO2: partial pressure of oxygen in arterial blood: NA: Not Applicable.