Branches in the decision tree and an overview of the predicted diagnoses
| Rule branch | Main outcome | Total leaf n (% total leaf) | ACOS n (% total) | COPD n (% total) | Asthma n (% total) | Other# n (% total) |
| FEV1/FVC ≥70% predicted | Asthma | 1415 (15.2) | 11 (0.8) | 3 (0.2) | 1108 (78.3) | 293 (20.7) |
| Onset age <38 years | ||||||
| ≥1 allergy | ||||||
| Reversibility <7% | ||||||
| FEV1/FVC ≥70% predicted | Asthma | 724 (7.8) | 11 (1.5) | 1 (0.1) | 647 (89.4) | 65 (9.0) |
| Onset age <38 years | ||||||
| ≥1 allergy | ||||||
| Reversibility ≥7% | ||||||
| FEV1/FVC ≥70% predicted | Asthma | 829 (8.9) | 16 (1.9) | 5 (0.6) | 593 (71.5) | 215 (25.9) |
| Onset age <38 years | ||||||
| No allergy | ||||||
| Wheezing | ||||||
| FEV1/FVC ≥70% predicted | Asthma | 548 (5.9) | 11 (2.0) | 7 (1.3) | 276 (50.4) | 254 (46.4) |
| Onset age ≥38 years | ||||||
| ≥1 allergy | ||||||
| Reversibility <7% | ||||||
| FEV1/FVC ≥70% predicted | Asthma | 181 (1.9) | 8 (4.4) | 2 (1.1) | 133 (73.5) | 38 (21.0) |
| Onset age ≥38 years | ||||||
| ≥1 allergy | ||||||
| Reversibility ≥7% | ||||||
| FEV1/FVC <70% predicted | Asthma | 356 (3.8) | 35 (9.8) | 43 (12.2) | 219 (61.5) | 59 (16.6) |
| Never smoked | ||||||
| FEV1/FVC <70% predicted | ACOS | 783 (8.4) | 302 (38.6) | 252 (32.2) | 183 (23.4) | 46 (5.9) |
| Onset age <38 years | ||||||
| Smoked | ||||||
| FEV1/FVC <70% predicted | COPD | 1142 (12.3) | 164 (14.4) | 928 (81.3) | 19 (1.7) | 31 (2.7) |
| Onset age ≥38 years | ||||||
| Smoked | ||||||
| FEV1 <78% predicted | ||||||
| FEV1/FVC <70% predicted | COPD | 257 (2.8) | 26 (10.1) | 203 (79.0) | 11 (4.3) | 17 (6.6) |
| Onset age ≥38 years | ||||||
| Smoked | ||||||
| FEV1 ≥78% and <92% predicted | ||||||
| Reversibility <7% | ||||||
| FEV1/FVC <70% predicted | COPD | 168 (1.8) | 56 (33.3) | 79 (47.0) | 18 (10.7) | 15 (8.9) |
| Onset age ≥38 years | ||||||
| Smoked | ||||||
| FEV1 ≥78% and <92% predicted | ||||||
| Reversibility ≥7% | ||||||
| FEV1/FVC <70% predicted | COPD | 238 (2.6) | 32 (13.4) | 127 (53.4) | 32 (13.4) | 47 (19.7) |
| Onset age ≥38 years | ||||||
| Smoked | ||||||
| FEV1 ≥92% predicted | ||||||
| FEV1/FVC ≥70% predicted | Other# | 1961 (21.2) | 33 (1.7) | 61 (3.1) | 561 (28.6) | 1306 (66.6) |
| Onset age ≥38 years | ||||||
| No allergy | ||||||
| FEV1/FVC ≥70% predicted | Other# | 695 (7.5) | 6 (0.9) | 5 (0.7) | 323 (46.8) | 359 (51.7) |
| Onset age <38 years | ||||||
| No allergy | ||||||
| No wheezing |
ACOS: asthma–COPD overlap syndrome; COPD: chronic obstructive pulmonary disease; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity. #: “diagnosis unclear”, “indication of restriction” or “no disease”. Bold indicates diagnoses that were correctly predicted. Spirometry results were taken after admission of bronchodilation.