Table 1.
Cohort Characteristics and Disease Severity
| Variable | Overall (N = 1128) |
Mild (n = 709) |
Moderate (n = 371) |
Severe (n = 48) |
|---|---|---|---|---|
| Demographics/medical history | ||||
| Age, y, median (IQR) | 3.3 (1.5–7.1) | 3.4 (1.6–7.1) | 3.2 (1.3–6.7) | 3.2 (1.1–8.6) |
| Male sex | 615 (55) | 399 (56) | 193 (52) | 23 (48) |
| Race/ethnicity (n = 1122) | ||||
| Non-Hispanic white | 689 (61) | 412 (58) | 243 (65) | 34 (71) |
| Non-Hispanic black | 332 (29) | 234 (33) | 91 (25) | 7 (15) |
| Hispanic | 34 (3) | 13 (2) | 18 (5) | 3 (6) |
| Other | 67 (6) | 46 (6) | 17 (5) | 4 (8) |
| Smoke exposure | 475 (42) | 304 (43) | 151 (41) | 20 (42) |
| Past medical history | ||||
| Pneumonia | 250 (22) | 147 (21) | 89 (24) | 14 (29) |
| Prior pneumonia hospitalization | 100 (40) | 56 (38) | 37 (42) | 7 (50) |
| Asthma | 364 (32) | 232 (33) | 114 (31) | 18 (38) |
| Prematurity | 200 (18) | 120 (17) | 67 (18) | 13 (27) |
| Season | ||||
| Winter | 404 (36) | 248 (35) | 138 (37) | 18 (38) |
| Spring | 245 (22) | 151 (21) | 82 (22) | 12 (25) |
| Summer | 155 (14) | 106 (15) | 44 (12) | 5 (10) |
| Fall | 324 (29) | 204 (29) | 107 (29) | 13 (27) |
| Illness symptoms/history of present illness | ||||
| Symptom duration, d, median (IQR) | 2 (1–4) | 2 (1–4) | 3 (1–5) | 2 (1–4) |
| Fever at home | 996 (87) | 616 (87) | 327 (88) | 43 (90) |
| Fever duration, d, median (IQR) | 4 (2–7) | 5 (2–7) | 4 (2–7) | 3.5 (2–6) |
| Decreased oral intake | 702 (62) | 415 (59) | 257 (69) | 30 (62) |
| Difficulty breathing | 916 (81) | 547 (77) | 325 (88) | 44 (92) |
| Rapid breathing | 835 (74) | 483 (68) | 310 (84) | 42 (88) |
| Wheezing | 724 (64) | 446 (63) | 247 (67) | 31 (65) |
| Vomiting | 577 (51) | 346 (49) | 207 (56) | 24 (50) |
| Abdominal pain | 360 (32) | 233 (33) | 116 (31) | 11 (23) |
| Physical examination | ||||
| Temperature (n = 1127), median (IQR) | 37.8 (37.2–38.7) | 37.8 (37.1–38.6) | 38 (37.4–38.8) | 37.9 (37.4–39.3) |
| Respiratory rate, median (IQR) | 42 (30–55.2) | 39 (28–48) | 49 (37–60) | 52 (44–66) |
| Heart rate (n = 1127), median (IQR) | 152 (130–168) | 144 (124–162) | 160 (140–174) | 168 (149.5–186.5) |
| SBP (n = 1019), median (IQR) | 107 (98–116) | 110 (100–118) | 105 (96–114) | 99.5 (89.5–109.5) |
| PF ratioa (n = 1034), median (IQR) | 452.4 (350–461.9) | 457.1 (447.6–466.7) | 413.4 (276–452.4) | 339.3 (140–447.6) |
| Retractions (n = 1097) | 476 (43) | 217 (31) | 225 (62) | 34 (72) |
| Grunting (n = 1095) | 76 (7) | 25 (4) | 41 (11) | 10 (21) |
| Nasal flaring (n = 1091) | 124 (11) | 45 (7) | 68 (19) | 11 (23) |
| Crackles (n = 1095) | 342 (31) | 189 (27) | 138 (38) | 15 (32) |
| Rhonchi (n = 1096) | 385 (32) | 221 (32) | 143 (40) | 21 (45) |
| Wheezing (n = 1097) | 325 (30) | 187 (27) | 116 (32) | 22 (47) |
| Decreased breath sounds (n = 1096) | ||||
| Not decreased | 719 (66) | 490 (71) | 208 (58) | 21 (45) |
| Focally decreased | 256 (23) | 139 (20) | 100 (28) | 17 (36) |
| Diffusely decreased | 121 (11) | 59 (9) | 53 (15) | 9 (19) |
| Abnormal skin color (n = 1096) | 92 (8) | 30 (4) | 53 (15) | 9 (19) |
| Capillary refill ≥3 sec (n = 1084) | 144 (13) | 51 (8) | 78 (22) | 15 (33) |
| Chest radiography findings | ||||
| Radiologist interpretation | ||||
| No atelectasis or pneumonia | 383 (34) | 312 (44) | 62 (17) | 9 (19) |
| Favoring atelectasis | 493 (44) | 266 (38) | 206 (56) | 21 (44) |
| Atelectasis vs pneumonia | 50 (4) | 26 (4) | 21 (6) | 3 (6) |
| Favoring pneumonia | 202 (18) | 105 (15) | 82 (22) | 15 (31) |
| Radiographic infiltrate pattern | ||||
| None | 383 (34) | 312 (44) | 62 (17) | 9 (19) |
| Unilateral and single lobe | 351 (31) | 201 (28) | 134 (36) | 16 (33) |
| Unilateral and multifocal | 52 (5) | 24 (3) | 25 (7) | 3 (6) |
| Bilateral/multifocal | 342 (30) | 172 (24) | 150 (40) | 20 (42) |
| Hyperinflation | 276 (24) | 137 (19) | 125 (34) | 14 (29) |
| Pleural effusion | 83 (7) | 28 (4) | 45 (12) | 10 (21) |
| Airways (ie, peribronchial) involvement | 601 (53) | 343 (48) | 232 (63) | 26 (54) |
Data are presented as No. (%) unless otherwise indicated.
Abbreviations: IQR, interquartile range; PF, partial pressure of oxygen/fraction of inspired oxygen; SBP, systolic blood pressure.
aTo evaluate both oxygen saturation and oxygen requirement, oxygenation was reported using the oxygen saturation/fraction of inspired oxygen (FiO2) ratio, which is a noninvasive proxy for partial pressure of oxygen/FiO2 [15–17].