Baseline characteristics of study participants*†
| ULDCT (n=1208) | CXR (n=1210) | |
| Mean age (±SD), years | 59.0 (18.1) | 59.0 (18.6) |
| Female sex | 613 (50.7) | 587 (48.5) |
| Comorbidity | ||
| Charlson Comorbidity Index (IQR)‡ | 3.0 (1.0–5.0) | 3.0 (1.0–5.0) |
| Immunocompromised | 285 (23.6) | 246 (20.3) |
| Malignancy§ | 229 (19.0) | 222 (18.3) |
| Diabetes§ | 230 (19.0) | 245 (20.2) |
| Pulmonary disease | ||
| Chronic obstructive pulmonary disease§ | 175 (14.5) | 179 (14.8) |
| Asthma | 141 (11.7) | 109 (9.0) |
| Interstitial lung disease | 29 (2.4) | 28 (2.3) |
| Cystic fibrosis | 14 (1.2) | 14 (1.2) |
| Cardiac disease | ||
| Myocardial infarction§ | 159 (13.2) | 169 (14.0) |
| Chronic cardiac failure§ | 98 (8.1) | 98 (8.1) |
| Neurological disease§ | 140 (11.6) | 149 (12.3) |
| Kidney disease§ | 104 (8.6) | 119 (9.8) |
| Thromboembolic disease | 92 (7.6) | 107 (8.8) |
| Presenting symptoms | ||
| Dyspnoea | 663 (54.9) | 695 (57.4) |
| Cough | 679 (56.2) | 631 (52.1) |
| Fever | 514 (42.5) | 468 (38.7) |
| Thoracic pain | 442 (36.6) | 460 (38.0) |
| Sputum production | 378 (31.3) | 354 (29.3) |
| Haemoptysis | 54 (4.5) | 41 (3.4) |
| Confusion | 50 (4.1) | 41 (3.4) |
| Clinical question on radiology request form | ||
| Pneumonia | 837 (69.3) | 822 (67.9) |
| Pulmonary congestion | 76 (6.3) | 114 (9.4) |
| Bronchitis | 108 (8.9) | 57 (4.7) |
| Pneumothorax | 36 (3.0) | 69 (5.7) |
| Pleural effusion | 35 (2.9) | 46 (3.8) |
| Pulmonary tumour | 10 (0.8) | 10 (0.8) |
| Atelectasis | 4 (0.3) | 3 (0.3) |
| Pulmonary metastases | 4 (0.3) | 3 (0.2) |
| Other | 90 (7.5) | (6.5) |
*See online supplemental table S5 for a detailed composition of this table including specification of variables.
†Values are numbers (percentages) unless otherwise specified.
‡Charlson Comorbidity Index, excluding AIDS. Predicts 10-year survival in patients with multiple comorbidities.32
§Variables included in the Charlson Comorbidity Index.32
CXR, chest X-ray; ULDCT, ultra-low-dose chest CT.