Baseline characteristics of subjects
| Demographic characteristics | All (N=188) | Semarang (N=47) | Yogyakarta (N=52) | Tangerang (N=89) | P value |
| Age, median (IQR) months | 9 (5–20) | 9 (5.5–21) | 8 (4–13.3) | 11 (5–20) | 0.442 |
| Gender, male, (%) | 103 (54.7) | 29 (61.7) | 26 (50) | 48 (53.9) | 0.493 |
| Household characteristics, (%) | |||||
| Low education of parents* | 163 (86.7) | 37 (78.7) | 43 (82.7) | 84 (94.3) | 0.019 |
| Living in a dense neighbourhood† | 121 (64.4) | 19 (40.4) | 42 (80.8) | 60 (67.4) | <0.001 |
| Exposure to cigarette smoke | 120 (63.8) | 24 (51.1) | 27 (51.9) | 69 (77.5) | 0.001 |
| Sick household contact <14 days | 109 (58.0) | 22 (46.8) | 43 (82.7) | 44 (49.4) | <0.001 |
| Living near waste disposal | 70 (37.2) | 12 (25.5) | 29 (55.8) | 29 (32.6) | 0.004 |
| Attending daycare | 4 (2.1) | 2 (4.3) | 1 (1.9) | 1 (1.1) | 0.374 |
| Medical history (%) | |||||
| Developmental delay | 52 (27.7) | 16 (34.0) | 21 (40.4) | 15 (16.8) | 0.003 |
| Congenital heart disease | 49 (26.1) | 16 (34.0) | 24 (46.2) | 9 (10.1) | <0.001 |
| Low birth weight | 46 (24.4) | 12 (25.5) | 20 (38.5) | 14 (15.7) | 0.011 |
| Severe malnutrition‡ | 35 (18.6) | 10 (21.3) | 13 (25.0) | 12 (13.5) | 0.205 |
| Premature baby | 34 (18.1) | 4 (8.5) | 16 (30.8) | 14 (15.7) | 0.012 |
| Neurological disorder | 25 (13.3) | 5 (10.6) | 17 (32.7) | 3 (3.4) | <0.001 |
| Tuberculosis (recent/cured) | 10 (5.3) | 4 (8.5) | 2 (3.8) | 4 (4.5) | 0.588 |
| Asthma | 9 (4.8) | 3 (6.4) | 1 (1.9) | 5 (5.6) | 0.563 |
| HIV disease§ | 2 (1.1) | 1 (2.1) | 1 (1.9) | 0 (0) | 0.315 |
| Immunisation history, fully vaccinated for age¶ (%): | |||||
| Measles | 141 (75.0) | 38 (80.9) | 41 (78.8) | 62 (69.7) | 0.175 |
| DPT-Hib | 105 (55.9) | 30 (63.8) | 25 (48.1) | 50 (56.2) | 0.233 |
| Pneumococcus | 4 (2.1) | 0 (0) | 4 (7.7) | 0 (0) | 0.009 |
| Influenza | 2 (1.1) | 0 (0) | 2 (3.8) | 0 (0) | 0.132 |
| Symptoms and signs (%) | |||||
| Shortness of breath | 174 (92.6) | 41 (87.2) | 48 (92.3) | 85 (95.5) | 0.214 |
| Cough | 171 (91.0) | 40 (85.1) | 42 (80.8) | 89 (100) | <0.001 |
| Intercostal retraction | 171 (91.0) | 43 (91.5) | 52 (100) | 76 (85.4) | 0.005 |
| Rhonchi | 168 (89.4) | 42 (89.4) | 39 (75.0) | 87 (97.8) | <0.001 |
| Fever | 152 (80.9) | 34 (72.3) | 35 (67.3) | 83 (93.3) | <0.001 |
| Chest indrawing | 125 (66.5) | 36 (76.6) | 43 (82.7) | 46 (51.7) | <0.001 |
| Fast breathing | 80 (42.6) | 15 (31.9) | 43 (82.7) | 22 (24.7) | <0.001 |
| SpO2<90% and/or cyanosis | 43 (22.9) | 7 (14.9) | 17 (32.7) | 19 (21.3) | 0.098 |
| Diarrhoea | 36 (19.1) | 6 (12.8) | 4 (7.7) | 26 (29.2) | 0.003 |
| Wheezing | 35 (18.6) | 9 (19.1) | 10 (19.2) | 16 (18.0) | 1 |
| Vomiting | 14 (7.4) | 4 (8.5) | 5 (9.6) | 5 (5.6) | 0.595 |
| Inability to drink | 13 (6.9) | 4 (8.5) | 5 (9.6) | 4 (4.5) | 0.425 |
| Decreased consciousness | 7 (3.7) | 1 (2.1) | 1 (1.9) | 5 (5.6) | 0.612 |
| Seizure | 6 (3.2) | 1 (2.1) | 0 (0) | 5 (5.6) | 0.203 |
| Leucocyte count, median (IQR)×103 /uL | 14.0 (10.4–18.9) | 14.9 (11.1–18.8) | 12.1 (9.8–17.8) | 14.0 (10.4–19.0) | 0.356 |
| Neutrophil-lymphocyte ratio, median (IQR) | 1.4 (0.9–2.8) | 1.3 (0.9–2.6) | 1.0 (0.6–2.0) | 1.9 (1.1–3.2) | 0.367 |
| CRP, median (IQR) mg/L | 9.0 (3.6–28.0) | 11.8 (1.6–23.3) | 9.0 (4.9–21.8) | 8.4 (1.5–34.1) | 0.665 |
| PCT, median (IQR) ng/mL | 0.2 (0.1–1.7) | 0.2 (0.1–1.5) | 0.2 (0.1–1.0) | 0.2 (0.1–2.6) | 0.912 |
| Severe pneumonia (WHO Classification 2014 version) (%) | 89 (47.3) | 26 (55.3) | 26 (50.0) | 37 (41.6) | 0.281 |
| CXR findings (%): | |||||
| Interstitial infiltrate | 131 (69.7) | 26 (55.3) | 30 (57.7) | 75 (84.3) | <0.001 |
| Alveolar infiltrate | 125 (66.5) | 41 (87.2) | 44 (84.6) | 40 (44.9) | <0.001 |
| Pleural effusion | 5 (2.7) | 1 (2.1) | 2 (3.8) | 2 (2.2) | 0.85 |
| Antibiotic administration prior to blood culture (%) | 150 (79.8) | 39 (83.0) | 49 (94.2) | 62 (69.7) | 0.002 |
*Low education of parents was defined by highest level of parents’ formal education being high school diploma or less.
†A densely populated neighbourhood was defined as >200 people/km2 or <8 m2/person in the subject’s home.
‡Severe malnutrition was defined as weight for height below −3 SD from the median of the WHO Child Growth Standards.
§Subjects were tested for HIV infection if a parent/guardian provided consent and a specimen was available (n=160).
¶Full vaccination was defined as being up to date for age per vaccination schedule at study enrolment.
CRP, C reactive protein; CXR, chest X-ray; PCT, procalcitonin.