Table 1.
Baseline characteristics according to categories of oxygen saturation
| Oxygen saturation level (%) | |||
|---|---|---|---|
| ≥98 | 97 | ≤96 | |
| Observation periods | 6169 (53.9) | 2951 (28.8) | 2318 (20.3) |
| Age (y) | 63.1 (9.7) | 65.7 (8.9) | 67.1 (8.3) |
| Sex (male) | 2386 (38.6) | 1435 (48.6) | 1136 (49.0) |
| Daily smoking | 1288 (21.1) | 612 (21.0) | 558 (24.3) |
| Body mass index (kg/m2) | 26.0 (3.8) | 27.7 (4.0) | 28.5 (4.7) |
| History of CVD | 768 (12.5) | 472 (16.0) | 465 (20.1) |
| History of cancer | 480 (7.8) | 264 (9.0) | 212 (9.2) |
| COPD stages | |||
| Airflow without obstruction | 4744 (80.9) | 2127 (75.8) | 1483 (68.0) |
| Stage I‐II | 1066 (18.2) | 607 (21.7) | 555 (25.4) |
| Stage III‐IV | 52 (0.9) | 69 (2.5) | 144 (6.6) |
| Dyspnea when walking calmly | 131 (2.1) | 95 (3.2) | 130 (5.6) |
| Dyspnea while washing and dressing | 150 (2.4) | 120 (4.1) | 183 (7.9) |
| Dyspnea at rest | 96 (1.6) | 53 (1.8) | 56 (2.4) |
| Cough daily in periods of the year | 965 (15.6) | 554 (18.8) | 564 (24.3) |
| Chronic cough | 580 (9.4) | 361 (12.2) | 405 (17.5) |
| Productive cough (in periods of the year) | 649 (10.5) | 379 (12.8) | 435 (18.8) |
Values are n (%) or mean ± SD.
Abbreviations: COPD, chronic obstructive pulmonary disease; CVD, cardiovascular disease.