| GOLD I | GOLD II | GOLD III | GOLD IV | p-value | |
| Subjects | 62 | 128 | 151 | 71 | |
| Age years | 50.3±15.7 | 54.9±11 | 51.4±10 | 50.3±9.8 | * |
| BMI# kg·m−2 | 24.5±4.4 | 25.3± 3.5 | 25.1±4.1 | 23.6±4.1 | |
| Male | 25 (40.3) | 66 (51.6) | 100 (66.2) | 58 (81.7) | *** |
| Smoking | *** | ||||
| Current | 10 (16.4) | 13 (10.2) | 9 (6) | 5 (7.1) | |
| Former | 17 (27.9) | 76 (59.4) | 121 (80.1) | 57 (81.4) | |
| Never | 34 (55.7) | 39 (30.5) | 21 (13.9) | 8 (11.4) | |
| Pack-years | 12.6±14.2 | 21±14.4 | 24.3±13.5 | 26.4±16.7 | ** |
| Reason for AATD diagnosis | |||||
| Lung disease | 27 (44.3) | 103 (80.5) | 136 (90.1) | 67 (94.4) | |
| Liver disease | 7 (11.5) | 1 (3.1) | 4 (2.6) | 0 (0) | |
| Family screening | 23 (37.7) | 17 (13.3) | 11 (7.3) | 4 (5.6) | |
| Other | 4 (6.6) | 4 (3.1) | 0 (0) | 0 (0) | |
| Age at diagnosis years | 44.8±17.8 | 51.7±12.3 | 48.8±10.1 | 47.7±9.7 | ** |
| Main symptom dyspnoea % | 46.41 | 74.8 | 79.9 | 77.1 | |
| Age at symptom onset years | 37.8±18.4 | 40.9±12.6 | 39.9±12.1 | 37.5±11.1 | |
| Diagnostic delay years | 9.9±17.8 | 9.5±13.7 | 8.1±9.4 | 9.5±9.3 | |
| Lung disease | |||||
| Chronic bronchitis | 15 (24.2) | 49 (38.3) | 56 (37.1) | 16 (22.5) | * |
| Asthma | 10 (16.1) | 15 (11.7) | 15 (10) | 3 (4.2) | |
| Emphysema | 41 (66.1) | 101 (78.9) | 127 (84.1) | 61 (85.9) | * |
| Bronchiectasis | 14 (23.3) | 33 (25.8) | 34 (22.5) | 10 (14.1) | |
| Others | 6 (12.8) | 3 (3) | 16 (12.2) | 4 (6.3) | |
| Pneumonia | 12 (19.4) | 38 (29.7) | 38 (25.2) | 19 (26.8) | |
| Respiratory medication | 32 (52.5) | 107 (88.4) | 131 (92.9) | 64 (98.5) | *** |
| Oxygen therapy | 3 (5.4) | 12 (10.3) | 30 (21.3) | 24 (37.5) | *** |
| Augmentation therapy | 12 (19.4) | 62 (48.4) | 89 (58.9) | 36 (50.7) | *** |
| Pulmonary function | *** | ||||
| FEV1 L·s−1 | 2.8±0.8 | 1.8±0.5 | 1.2±0.3 | 0.8±0.2 | *** |
| FEV1 % pred | 98.7±16.3 | 62.7±8.3 | 36.9±5.7 | 23.4±4 | *** |
| FVC L | 3.9±1 | 3.3±1.2 | 3±1 | 2.3±0.9 | *** |
| FVC % pred | 104.8±15.7 | 86.6±18.2 | 71.7±18.2 | 50.7±15.6 | *** |
| FEV1/FVC % | 71.1±11.1 | 55.2±110.8 | 43.6±10.6 | 36.9±9 | *** |
Values are given as n, mean±sd or n (%), unless otherwise stated. BMI: body mass index; AATD: α1-antitrypsin deficiency; FEV1: forced expiratory volume in 1 s; % pred: % predicted; FVC: forced vital capacity. #: not available for patients from the Italian registry. *: p<0.05; **: p<0.01; ***: p<0.001.