Table 2. Baseline characteristics of the subjects according to the GOLD stage (I + II vs. III + IV) and GOLD group (A + B vs. C + D).
| Parameters | Stage I + II | Stage III + IV | P value | Grade A + B | Grade C + D | P value | ||||
|---|---|---|---|---|---|---|---|---|---|---|
| No. | value | No. | value | No. | value | No. | value | |||
| Age (yr, mean ± SD) | 569 | 69.8 ± 7.8 | 343 | 70.0 ± 7.9 | 0.828 | 520 | 69.7 ± 7.9 | 398 | 70.1 ± 7.8 | 0.550 |
| Male, No. (%) | 570 | 516 (90.5) | 342 | 315 (92.1) | 0.417 | 520 | 474 (91.2) | 398 | 362 (91.0) | 0.917 |
| BMI (kg/m2, mean ± SD) | 562 | 23.4 ± 3.3 | 340 | 21.6 ± 3.3 | < 0.001 | 513 | 23.4 ± 3.3 | 391 | 21.8 ± 3.4 | < 0.001 |
| Current smoker | 567 | 169 (29.8) | 338 | 82 (24.3) | 0.076 | 519 | 155 (29.9) | 391 | 98 (25.1) | 0.253 |
| Smoking, pack/yr, (mean ± SD) | 487 | 43.8 ± 24.3 | 297 | 44.0 ± 26.0 | 0.905 | 447 | 43.5 ± 23.9 | 341 | 44.3 ± 27.0 | 0.649 |
| Number of acute exacerbation during one year before enroll | 565 | 340 | 521 | 396 | ||||||
| Mean ± SD | 0.4 ± 1.6 | 0.9 ± 1.6 | < 0.001 | 0.1 ± 0.3 | 1.2 ± 2.3 | < 0.001 | ||||
| 0 | 457 (80.9) | 204 (60.0) | < 0.001 | 457 (87.7) | 212 (53.5) | < 0.001 | ||||
| 1 | 64 (11.3) | 78 (22.9) | 64 (12.3) | 79 (20.0) | ||||||
| ≥ 2 | 44 (7.8) | 58 (17.1) | 0 (0.0) | 105 (26.5) | ||||||
| Number of comorbidities | 571 | 1.7 ± 1.3 | 343 | 1.8 ± 1.5 | 0.162 | 521 | 1.6 ± 1.3 | 399 | 1.8 ± 1.5 | 0.082 |
| Education level | 569 | 343 | 0.049 | 519 | 398 | 0.043 | ||||
| Middle school and below | 312 (54.8) | 214 (62.4) | 279 (53.8) | 246 (61.8) | ||||||
| High school | 176 (30.9) | 95 (27.7) | 164 (31.6) | 108 (27.1) | ||||||
| College and above | 81 (14.2) | 34 (9.9) | 76(14.6) | 44 (11.1) | ||||||
| Lung function | ||||||||||
| FEV1/FVC (%, mean ± SD) | 570 | 54.5 ± 9.6 | 343 | 39.9 ± 10.0 | < 0.001 | 520 | 54.7 ± 9.7 | 388 | 41.3 ± 10.7 | < 0.001 |
| Post BD FEV1 (%, mean ± SD) | 571 | 66.0 ± 11.6 | 343 | 38.9 ± 7.6 | < 0.001 | 521 | 66.2 ± 11.5 | 387 | 41.6 ± 11.4 | < 0.001 |
| FEV1 (L, mean ± SD) | 571 | 1.8 ± 0.5 | 343 | 1.0 ± 0.3 | < 0.001 | 521 | 1.8 ± 0.5 | 389 | 1.1 ± 0.5 | < 0.001 |
| FVC (L, mean ± SD) | 571 | 3.3 ± 0.8 | 343 | 2.7 ± 0.7 | < 0.001 | 521 | 3.3 ± 0.8 | 389 | 2.7 ± 0.8 | < 0.001 |
| TLC (L, mean ± SD) | 393 | 5.6 ± 0.8 | 193 | 5.6 ± 0.8 | 0.824 | 364 | 5.6 ± 0.8 | 226 | 5.6 ± 0.8 | 0.550 |
| 6MWD (meters, mean ± SD) | 474 | 375.9 ± 112.9 | 250 | 344.2 ± 120.1 | < 0.001 | 431 | 376.4 ± 110.9 | 294 | 349.8 ± 124.4 | < 0.001 |
| Subjects requiring oxygen during/after 6MWD | 466 | 2 (0.4) | 242 | 0 (0.0) | 0.549 | 422 | 2 (0.5) | 286 | 0 (0.00) | 0.518 |
| Symptom scores | ||||||||||
| CAT score (mean ± SD) | 541 | 13.9 ± 6.9 | 335 | 18.3 ± 8.1 | < 0.001 | 493 | 13.5 ± 6.7 | 389 | 18.1 ± 8.3 | < 0.001 |
| CAT score | 151 (27.9) | 51 (15.2) | < 0.001 | 146 (29.6) | 65 (16.7) | < 0.001 | ||||
| CAT score ≥ 10 | 390 (72.1) | 284 (84.8) | < 0.001 | 347 (70.4) | 324 (83.3) | < 0.001 | ||||
| mMRC score (mean ± SD) | 571 | 1.4 ± 0.9 | 343 | 2.0 ± 1.0 | < 0.001 | 521 | 1.3 ± 0.8 | 399 | 1.9 ± 1.1 | < 0.001 |
| mMRC score < 2 | 367 (64.3) | 122 (35.6) | < 0.001 | 343 (65.8) | 153 (38.4) | < 0.001 | ||||
| mMRC score ≥ 2 | 204 (35.7) | 221 (64.4) | 178 (34.2) | 246 (61.7) | ||||||
| SGRQ-C | ||||||||||
| Symptom | 571 | 40.4 ±19.1 | 343 | 50.9 ± 21.8 | < 0.001 | 521 | 39.2 ± 18.7 | 398 | 50.7 ± 21.6 | < 0.001 |
| Activity | 570 | 40.3 ±23.8 | 343 | 56.7 ± 29.2 | < 0.001 | 520 | 38.9 ± 23.4 | 398 | 55.8 ± 29.3 | < 0.001 |
| Impact | 571 | 21.0 ±19.8 | 343 | 34.3 ± 26.2 | < 0.001 | 521 | 19.5 ± 18.7 | 398 | 34.3 ± 26.1 | < 0.001 |
| Total | 570 | 30.4 ± 16.5 | 342 | 42.9 ± 21.6 | < 0.001 | 520 | 29.1 ± 15.6 | 397 | 42.6 ± 21.6 | < 0.001 |
GOLD, global initiative for chronic obstructive lung disease; SD, standard deviation; BMI, body mass index; FEV1, forced expiratory volume in one second; FVC, forced vital capacity; TLC, total lung capacity; 6MWD, six minutes walk distance test; CAT, COPD assessment test; mMRC, modified Medical Research Council dyspnea scale; SGRQ-C, St. George’s respiratory questionnaire.