Table 3.
Baseline characteristics for the base case study population (categories based on Swanney prediction equations [6])
| Total cohort (n = 3,324) |
Non-obstructed (n = 2,406) |
Discordant (n = 389) |
Obstructed (n = 529) |
p value | |
|---|---|---|---|---|---|
| LLN*-Fixed- | LLN*-Fixed+ | LLN* + Fixed+ | |||
| Follow-up time, years (SD) | 3.4 (1.4) | 3.4 (1.4) | 3.2 (1.4) | 3.4 (1.5) | 0.592 |
| Males, n (%) | 1,500 (45) | 894 (37) | 245 (63) | 361 (68) | < 0.001 |
| Age, mean (SD) | 58.1 (11.0) | 56.2 (10.5) | 67.0 (10.1) | 60.3 (10.2) | < 0.001 |
| 40-49, n (%) | 918 (28) | 798 (33) | 30 (8) | 90 (17) | |
| 50-59, n (%) | 1,003 (30) | 758 (31) | 66 (17) | 179 (34) | |
| 60-69, n (%) | 827 (25) | 553 (23) | 118 (30) | 156 (29) | |
| 70-79, n (%) | 512 (15) | 277 (12) | 144 (37) | 91 (17) | |
| > 80, n (%) | 64 (2) | 20 (1) | 31 (8) | 13 (3) | < 0.001 |
| Height, m | 1.69 (0.1) | 1.68 (0.1) | 1.73 (0.1) | 1.70 (0.1) | < 0.001 |
| BMI, kg/m [2] (SD) | 27.5 (5.0) | 28.2 (5.2) | 27.0 (4.2) | 25.0 (4.0) | < 0.001 |
| Smoking status, n (%) | |||||
| Never | 956 (29) | 864 (36) | 59 (15) | 33 (6) | |
| Former | 1,360 (41) | 964 (40) | 192 (49) | 204 (39) | |
| Current | 1,008 (30) | 578 (24) | 138 (36) | 292 (55) | < 0.001 |
| Respiratory medication use, n (%) | |||||
| Short-acting bronchodilators | 1,436 (43) | 1,061 (44) | 147 (38) | 228 (43) | 0.066 |
| Long-acting bronchodilators | 1,174 (35) | 841 (35) | 144 (37) | 189 (36) | 0.715 |
| Inhaled corticosteroids | 1,972 (59) | 1,550 (64) | 185 (48) | 237 (45) | < 0.001 |
| FEV1 | |||||
| Prebronchodilator, liters (SD) | 2.28 (0.74) | 2.46 (0.71) | 2.02 (0.65) | 1.64 (0.51) | < 0.001 |
| as % predicted* (SD) | 74.6 (17.9) | 81.1 (14.5) | 65.3 (12.1) | 51.7 (12.8) | < 0.001 |
| Postbronchodilator, liters (SD) | 2.46 (0.77) | 2.63 (0.74) | 2.21 (0.68) | 1.85 (0.56) | < 0.001 |
| as % predicted* (SD) | 80.2 (17.4) | 86.5 (14.1) | 71.7 (12.3) | 58.1 (13.2) | < 0.001 |
| FVC | |||||
| Prebronchodilator, liters (SD) | 3.23 (0.95) | 3.22 (0.95) | 3.24 (1.03) | 3.26 (0.91) | 0.708 |
| Postbronchodilator, liters (SD) | 3.35 (0.96) | 3.30 (0.95) | 3.43 (1.03) | 3.53 (0.92) | < 0.001 |
| FEV1/FVC | |||||
| Prebronchodilator (SD) | 0.71 (0.12) | 0.77 (0.07) | 0.63 (0.05) | 0.51 (0.08) | < 0.001 |
| Postbronchodilator (SD) | 0.74 (0.12) | 0.80 (0.05) | 0.65 (0.03) | 0.52 (0.08) | < 0.001 |
BMI: body mass index; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; LNN: lower limit of normal; SD: standard deviation
* based on Swanney prediction equations [6]