Distributions of candidate predictors in the study cohort
| Candidate predictor | Overall | No sepsis | Sepsis | P value |
| n | 2628 | 2331 | 297 | |
| Infant risk factors | ||||
| Gestational age (weeks) | 38.0 [37.0–40.0] | 38.0 [37.0–40.0] | 38.0 [37.0–40.0] | 0.03 |
| Birth weight (g) | 2950 [2400–3350] | 2900 [2400–3350] | 3000 [2600–3350] | 0.04 |
| Maternal risk factors (%) | ||||
| Maternal fever | 14 (0.5) | 8 (0.3) | 6 (2.0) | 0.003 |
| Offensive liquor | 163 (6) | 131 (6) | 32 (11) | 0.001 |
| PROM | 303 (12) | 257 (11) | 46 (15) | 0.03 |
| Infant clinical features | ||||
| Grunting at triage (%) | 750 (29) | 654 (28) | 96 (32) | 0.13 |
| Cyanosis at triage* (%) | 69 (2.6) | 60 (2.6) | 9 (3.0) | 0.6 |
| Seizures at triage* (%) | 14 (0.5) | 10 (0.4) | 4 (1.3) | 0.06 |
| Respiratory rate (breaths/min) | 56 [48–68] | 56 [48–68] | 60 [50–72] | <0.001 |
| Heart rate (beats/min) | 138 [126–146] | 138 [126–146] | 139 [127–150] | 0.01 |
| Temperature (°C) | 36.5 [36.0–37.0] | 36.5 [36.0–36.9] | 36.9 [36.2–38.0] | <0.001 |
| Fontanelle* (%) | 0.9 | |||
| Flat | 2608 (99) | 2312 (99) | 296 (100) | |
| Sunken | 10 (0.4) | 9 (0.4) | 1 (0.3) | |
| Bulging | 10 (0.4) | 10 (0.4) | 0 (0) | |
| Activity† (%) | <0.001 | |||
| Alert | 2152 (82) | 1933 (83) | 219 (74) | |
| Lethargic | 382 (15) | 327 (14) | 55 (19) | |
| Irritable | 62 (2.4) | 45 (1.9) | 17 (6) | |
| Seizures | 14 (0.5) | 9 (0.4) | 5 (1.7) | |
| Coma | 18 (0.7) | 17 (0.7) | 1 (0.3) | |
| Nasal flaring (%) | 912 (35) | 791 (34) | 121 (41) | 0.02 |
| Chest retractions (%) | 986 (38) | 848 (36) | 138 (46) | <0.001 |
| Grunting (%) | 421 (16) | 360 (15) | 61 (21) | 0.03 |
| Work of breathing (%) | <0.001 | |||
| Normal | 1405 (54) | 1263 (55) | 142 (48) | |
| Mildly increased | 413 (16) | 378 (16) | 35 (12) | |
| Moderately increased | 614 (24) | 529 (23) | 85 (29) | |
| Severely increased | 170 (6) | 139 (6) | 31 (11) | |
| Colour* (%) | 0.1 | |||
| Pink | 2507 (95) | 2220 (95) | 287 (97) | |
| Pale | 10 (0.4) | 7 (0.3) | 3 (1.0) | |
| Blue | 62 (2.4) | 58 (2.5) | 4 (1.3) | |
| Yellow | 49 (1.9) | 46 (2.0) | 3 (1.0) | |
| Abdominal distention* (%) | 28 (1.1) | 26 (1.1) | 2 (0.7) | 0.8 |
| Omphalitis* (%) | 6 (0.2) | 4 (0.2) | 2 (0.7) | 0.1 |
| Abnormal skin* (%) | 27 (1.0) | 23 (1.0) | 4 (1.3) | 0.5 |
| Vomiting* (%) | 0.3 | |||
| No | 2605 (99) | 2309 (99) | 296 (100) | |
| Yellow | 7 (0.3) | 7 (0.3) | 0 (0) | |
| Bilious | 13 (0.5) | 13 (0.6) | 0 (0) | |
| Blood stained | 3 (0.1) | 2 (<0.1) | 1 (0.3) |
Data are presented as median [quartile 1 to quartile 3] for continuous predictors or n (%) for categorical predictors. P values are from the Wilcoxon-Mann-Whitney U test for continuous predictors and Fisher’s exact test for categorical predictors. Distributions are presented for the observed data only, before multiple imputation of missing values.
*Eliminated from the final set of candidate predictors due to very skewed distributions.
†The three smallest categories of activity were collapsed into one ‘other’ category for model development.
PROM, prolonged rupture of membranes.