Comparison of concordant and discordant groups for airflow obstruction by FEV1/FVC fixed ratio and LLN†
| Variable | Concordant | Discordant (n=566) | |
|---|---|---|---|
| Smokers (Fixed−LLN−) (n=4491) | COPD (Fixed+LLN+) (n=2686) | ||
| Age | 57.1 (8.4) | 63.2 (8.6)** | 64.8 (8.4)** |
| Sex (% women) | 2061 (46) | 1162 (43) | 178 (31) |
| BMI | 29.2 (6.0) | 27.4 (5.8)** | 28.7 (5.6) |
| Race (% black) | 1760 (39) | 548 (20) | 79 (14) |
| Pack-years | 38.4 (20.9) | 53.2 (26.9)** | 49.5 (27.1)** |
| Oxygen therapy at baseline (%) | 70 (1.6) | 698 (26)** | 25 (4.4)** |
| FEV1 (litres) | 2.8 (0.7) | 1.6 (0.7)** | 2.4 (0.7)** |
| FEV1 % predicted | 92.5 (15.3) | 54.7 (21.8)** | 81.1 (14.9)** |
| FVC (litres) | 3.5 (0.9) | 3.1 (1.0)** | 3.6 (1) |
| FVC % predicted | 91.8 (14.9) | 81.9 (20.8)** | 90.7 (16.6) |
| FEV1/FVC | 0.78 (0.05) | 0.50 (0.13)** | 0.68 (0.02)** |
| Response to bronchodilator (%) | 424 (9) | 980 (37)** | 111 (20)** |
| TLC | 5.2 (1.3) | 6.1 (1.5)** | 5.9 (1.3)** |
| FRC | 2.7 (0.7) | 4.0 (1.2)** | 3.3 (0.8)** |
| 6MWD | 1469 (360) | 1226 (398)** | 1433 (381) |
| MMRC | 0.8 (1.2) | 1.9 (1.4)** | 0.9 (1.3) |
| BODE | 0.5 (1.0) | 2.6 (2.1)** | 0.7 (1.1)* |
| SGRQ total | 17.2 (18.1) | 36.9 (21.8)** | 19.7 (19)* |
| SGRQ symptoms | 21.9 (21.6) | 42.4 (24.9)** | 25.9 (23)** |
| SGRQ activity | 26.4 (26.1) | 52.6 (28.2)** | 29.1 (26.7) |
| SGRQ impact | 10.5 (15.6) | 26.4 (21.0)** | 12.5 (16.5)* |
| LAA950insp | 1.9 (2.6) | 13.2 (12.8)** | 4 (4.2)** |
| LAA856exp | 10.9 (9.7) | 38.8 (20.9)** | 19.4 (11.1)** |
| Perc15 | −904.4 (25.4) | −939.1 (28.7)** | −919.5 (21.3)** |
| Wall area (%) | 60.3 (3) | 62.5 (3.1)** | 60.9 (2.9)** |
All values expressed as mean (SD).
*p<0.05, **p<0.001.
†Statistical significance expressed in comparison with smokers without airflow obstruction (Fixed−LLN−).
6MWD, 6 min walk distance; BMI, body mass index; BODE, body mass index, airflow obstruction, dyspnea and exercise capacity index; FEV1, forced expiratory volume in the first second; FRC, forced residual capacity; FVC, forced vital capacity; LAA856exp, percentage low attenuation area<856 Hounsfield units at end expiration; LAA950insp, percentage low attenuation area<950 Hounsfield units at end inspiration; LLN, lower limit of normal; MMRC, Modified Medical Research Council dyspnea scale; Perc15, percentage of voxels below the 15th percentile; SGRQ, St George's Respiratory Questionnaire; TLC, total lung capacity.