Table 2.
Descriptive statistics of study participants according to severity of COPD (GOLD 2011)
| Characteristics | Severity of COPD
|
||||
|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | P-value | |
| Age (years) | 63.0 (53.0, 71.0) | 67.0 (59.0, 74.0) | 67.0 (60.0, 75.0) | 72.0 (66.0, 78.0) | <0.001 |
| Duration of COPD (years) | 5.0 (2.0, 10.0) | 8.0 (4.0, 11.0) | 10.0 (5.0, 15.0) | 10.0 (6.0, 19.0) | <0.001 |
| Pack-years | 35.5 (20.0, 52.5) | 40.0 (25.0, 61.3) | 45.0 (20.0, 64.0) | 60.0 (37.5, 83.6) | <0.001 |
| FEV1 before bronchodilation (%) | 80.0 (70.0, 87.0) | 65.0 (58.0, 71.0) | 52.0 (43.0, 67.0) | 43.0 (29.0, 54.5) | <0.001 |
| FEV1 after bronchodilation (%) | 82.0 (75.0, 90.0) | 68.0 (61.0, 75.0) | 58.0 (47.0, 74.0) | 46.0 (32.0, 59.0) | <0.001 |
| Number of exacerbations in the past year | 1.0 (0.0, 2.0) | 1.0 (0.0, 2.0) | 2.0 (1.0, 3.0) | 2.0 (1.0, 4.0) | <0.001 |
Notes: Data are presented as median (interquartile ranges) for numerical variables.
Abbreviations: COPD, chronic obstructive pulmonary disease; FEV1, forced expiratory volume in 1 second; GOLD, Global Initiative for Chronic Obstructive Lung Disease.