Table 1.
Characteristics of subjects
| Characteristic | NS | SNI | SCE |
| N | 17 | 12 | 12 |
| Gender (% male) | 35 | 58 | 58 |
| Age (years) | 31 ± 10 | 32 ± 14 | 46 ± 11 |
| BMI (kg/m2) | 24 ± 3 | 25 ± 3 | 25 ± 4 |
| Heart rate (bpm) | 68 ± 10 | 72 ± 11 | 70 ± 13 |
| Blood pressure (mm Hg) | |||
| Systolic | 116 ± 13 | 119 ± 15 | 128 ± 13 |
| Diastolic | 66 ± 11 | 65 ± 12 | 74 ± 7 |
| Creatinine (mg/dL) | 0.8 ± 0.1 | 0.8 ± 0.1 | 1.0 ± 0.2 |
| Pack-years | — | 15 ± 14 | 31 ± 15 |
| Age started smoking (years) | — | 17 ± 3 | 16 ± 4 |
| BDI | 11.9 ± 0.2 | 11.3 ± 1.2 | 11.2 ± 1.3 |
| Daily cough in past 2 weeks (%) | 6 | 33 | 50 |
| Prebronchodilator FEV1 (%) | 98.3 ± 8.9 | 84.9 ± 16.7 | 98.2 ± 23.5 |
| Prebronchodilator FVC (%) | 100.7 ± 10.5 | 91.7 ± 11.5 | 103.9 ± 15.6 |
| Prebronchodilator FEV1/FV ()% | 81.4 ± 7.0 | 77.2 ± 11.6 | 74.5 ± 4.9 |
| DLCO (%) | 92.7 ± 16.0 | 79.4 ± 10.4 | 75.7 ± 19.6 |
| MLD (HU) | −849 ± 36 | −848 ± 18 | −846 ± 21 |
| EI −950 HU (%) | 6.3 ± 5.9 | 4.1 ± 4.3 | 4.3 ± 3.8 |
| EI −910 HU (%) | 34.8 ± 16.9 | 28.3 ± 14.9 | 26.0 ± 12.5 |
| α −950 HU | 1.7 ± 0.3 | 1.7 ± 0.2 | 1.6 ± 0.4 |
| α −910 HU | 0.9 ± 0.4 | 1.1 ± 0.4 | 1.0 ± 0.2 |
Results are expressed as mean ± SD unless noted. Spirometry and DLCO is reported as percent predicted. BDI, baseline dyspnea index; BMI, body mass index; DLCO, diffusing capacity of the lung for carbon monoxide; EI, emphysema index; FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; MLD, mean lung density; NS, persons who had never smoked; SCE smokers with centralobular emphysema present on MDCT; SNI, smokers with normal CT imaging studies.