| Characteristic | Children with good quality sputum sample(n = 76) | Children with poor quality sputum sample or quality of sputum sample not analysed(n = 25) | Children without sputum induction(n = 32) |
| Age (years)* | 3.4 (1.7–6.8) | 7.5 (3.0–10.7) | 4.1 (2.0–7.5) |
| Male, n (%) | 36 (47%) | 15 (60%) | 15 (47%) |
| Underlying condition (%) | 24 (32%) | 8 (32%) | 16 (50%) |
| Asthma | 12 (16%) | 6 (24%) | 3 (9%) |
| Prematurity (gestational age ⩽36 weeks) | 6 (8%) | 0 (0%) | 1 (3%) |
| Atopy | 2 (3%) | 0 (0%) | 1 (3%) |
| Congenital heart disease | 2 (3%) | 0 (0%) | 2 (6%) |
| Neurological disease | 2 (3%) | 2 (8%) | 13 (41%) |
| Ongoing antibiotic treatment on admission (%) | 11 (15%) | 5 (20%) | 8 (25%) |
| Macrolide | 6 (8%) | 1 (4%) | 3 (9%) |
| Beta-lactam | 3 (4%) | 4 (16%) | 3 (9%) |
| Other | 2 (3%) | 0 (0%) | 2 (6%) |
| Symptoms and signs | |||
| Fever ⩾38.0°C (%) | 74 (97%) | 25 (100%) | 30 (94%) |
| Cough (%) | 72 (95%) | 23 (92%) | 25 (78%) |
| Dyspnoea (%) | 27 (36%) | 8 (32%) | 8 (25%) |
| Inflammatory parameters | |||
| CRP (mg/l)* | 128 (50–212) | 142 (39–259) | 107 (33–238) |
| WBC count (×109/l)* | 18.6 (9.8–25.6) | 14.5 (7.2–22.6) | 12.0 (9.2–19.6) |
| Chest radiograph finding | |||
| Alveolar infiltrates (%) | 67 (88%) | 21 (84%) | 29 (91%) |
| Interstitial infiltrates (%) | 11 (15%) | 4 (16%) | 3 (9%) |
| Pleural fluid (%) | 8 (11%) | 1 (4%) | 0 (0%) |
*Median (interquartile range).
CRP, C-reactive protein; WBC, white blood cells.