Table 2.
PFT Parameters
| Parameters | Never Smokers | Former Smokers | Current Smokers | P-value |
|---|---|---|---|---|
| n=83 | n=118 | n=156 | ||
| FEV1 (L) | 1.14 (0.77~1.56) | 1.18 (0.84~1.59) | 1.37 (0.95~1.77) *# | 0.005 |
| FEV1%pred | 49.6 (37~66.35) | 45.75 (31.2~57) | 45.4 (35.6~58.4) | 0.089 |
| FVC% pred | 70.2 (55.5~86.3) | 68.3 (51.8~79.5) | 67.05 (56.4~79.9) | 0.376 |
| FEV1/FVC (%) | 58.78 (48.63~63.74) | 52.38 (44.23~60.27) * | 53.68 (45.07~60.32) * | 0.007 |
| PEF %pred | 39.2 (28.25~51.2) | 37.5 (28~46.1) | 39 (29.85~48.8) | 0.599 |
| MMEF25–75% | 19.4 (14~28.9) | 18.6 (12.8~25) | 19.25 (13.7~27) | 0.598 |
| DLCO/VA (%) | 89.5±22.27 | 78.29±25.86* | 75.63±23.98* | <0.001 |
| RV/TLC (%) | 57.09±10.48 | 58.44±11.2 | 55.14±10.84 | 0.051 |
| Z5%pred | 182.1 (144.5~219.6) | 175.6 (143.1~207.4) | 169.6 (142.8~205.8) | 0.483 |
| R5 (kPa/L/s) | 0.58 (0.48~0.67) | 0.49 (0.42~0.58) * | 0.47 (0.39~0.56) * | <0.001 |
| R20 (kPa/L/s) | 0.36 (0.32~0.42) | 0.32 (0.28~0.36) * | 0.32 (0.29~0.37) * | <0.001 |
| R5-R20 (kPa/L/s) | 0.21 (0.12~0.28) | 0.16 (0.11~0.22) | 0.14 (0.09~0.2) * | 0.001 |
| X5 | −0.26 (−0.38~-0.17) | −0.22 (−0.32~-0.14) | −0.2 (−0.29~-0.14) * | 0.009 |
| Fres (Hz) | 23.34±5.79 | 22.73±5.07 | 21±5.23*# | 0.002 |
| Ax (kPa/L) | 2.18 (1.27~3.09) | 1.88 (1.06~2.57) | 1.49 (0.89~2.36) * | 0.003 |
Notes: *P < 0.05 compared with NS group; #P < 0.05 compared with FS group. Abbreviations: PFT pulmonary function test, FEV1 forced expiratory volume in 1 second, FVC forced vital capacity, FEV1/FVC forced expiratory volume in 1 sec/forced vital capacity, MMEF25–75% maximal mid expiratory flow, RV/TLC residual volume/total lung capacity, DLCO/VA ratio of carbon monoxide diffusion capacity to alveolar ventilation, %Pred, of the predicted value, Z5 total respiratory impedance, R5 resistance at 5 Hz, R20 resistance at 20 Hz, X5 reactance at 5 Hz, Fres response frequency, Ax reactance area.