Lung function
| Total | Chronic bronchitis | GOLD I | GOLD II | GOLD III | GOLD IV | |
| FEV1 % pred | 62.8±26.2# | 99.4±10.3 | 90.0±8.7 | 63.0±8.1 | 40.6±5.1 | 32.8±11.4 |
| FVC % pred | 94.1±21.6 | 105.7±13.0 | 114.2±14.8 | 97.0±16.2 | 84.3±16.3 | 72.8±20.7 |
| FEV1/FVC | 51.9±15.6 | 74.9±4.7 | 62.9±6.7 | 52.7±9.2 | 39.4±8.4 | 36.2±8.6 |
| Capillary PO2¶ mmHg | 69.9±8.5 | 76.2±9.6 | 71.0±6.7 | 71.2±7.7 | 69.7±6.1 | 60.4±5.8 |
| Capillary PCO2¶ mmHg | 37.8±4.8 | 34.9±3.8 | 36.0±3.8 | 37.6±3.9 | 38.0±3.3 | 42.6±6.1 |
Data are presented as mean±sd. GOLD: Global Initiative for Chronic Obstructive Lung Disease; FEV1: forced expiratory volume in one second; % pred: % predicted; FVC: forced vital capacity; PO2: partial pressure of oxygen; PCO2: partial pressure of carbon dioxide. #: FEV1 % pred for chronic obstructive pulmonary disease patients only was 56.3±22.6; ¶: data are missing for seven patients. 1 mmHg = 0.133 kPa.