Table 1. Baseline characteristics of all enrolled subjects in six groups.
| Characteristics | NSH | SH | NS-COPD | NS-control | S-COPD | S-control |
|---|---|---|---|---|---|---|
| Cases | 121 | 124 | 114 | 116 | 110 | 118 |
| Mean ages | 55.85±10.36 | 56.51±4.45 | 56.95±10.31 | 56.66±9.28 | 58.82±7.47 | 59.78±7.36 |
| Gender | 62/59 | 71/53 | 62/52 | 64/52 | 59/51 | 63/55 |
| Duration of cigarette smoking | – | 12.21±3.24 | – | – | 14.43±4.17 | 15.09±3.42 |
| Family medical history | – | – | – | – | – | – |
NS-COPD, non-smoking COPD; NS-control, non-smoking control; S-COPD, smoking COPD; S-control, smoking control; NSH, non-smoking healthy people; SH, smoking healthy people; COPD, chronic obstructive pulmonary disease.