Table 1. Patient Characteristics.
| Characteristic | Sample, No. (%) | Overall (N = 1821) | |
|---|---|---|---|
| Derivation (n = 908) | Validation (n = 913) | ||
| Age, mean (SD), d | 35.9 (14.8) | 36.1 (15.0) | 36.0 (14.9) |
| Age ≤28 d | 280 (30.8) | 275 (30.1) | 555 (30.5) |
| Female | 387 (42.6) | 378 (41.4) | 765 (42.0) |
| Race/ethnicity | |||
| White, non-Hispanic | 397 (43.7) | 384 (42.1) | 781 (42.9) |
| Black | 183 (20.2) | 183 (20.0) | 366 (20.1) |
| Asian | 20 (2.2) | 34 (3.7) | 54 (3.0) |
| Hispanic | 263 (29.0) | 272 (29.8) | 535 (29.4) |
| Other/missing | 45 (5.0) | 40 (4.4) | 85 (4.7) |
| Qualifying temperature, mean (SD), °C | 38.5 (0.5) | 38.5 (0.4) | 38.5 (0.4) |
| Duration of fever prior to ED visit, h | |||
| <12 | 569 (62.7) | 575 (63.0) | 1144 (62.8) |
| 12-24 | 265 (29.2) | 254 (27.8) | 519 (28.5) |
| >24 | 69 (7.6) | 75 (8.2) | 144 (7.9) |
| Unknown | 5 (0.6) | 9 (1.0) | 14 (0.8) |
| YOS, median (IQR) | 6.0 (6.0-8.0) | 6.0 (6.0-8.0) | 6.0 (6.0-8.0) |
| Clinician suspicion | |||
| <1% | 322 (35.5) | 361 (39.5) | 683 (37.5) |
| 1%-5% | 387 (42.6) | 366 (40.1) | 753 (41.4) |
| 6%-10% | 138 (15.2) | 127 (13.9) | 265 (14.6) |
| 11%-50% | 44 (4.8) | 42 (4.6) | 86 (4.7) |
| >50% | 10 (1.1) | 14 (1.5) | 24 (1.3) |
| Unknown | 7 (0.8) | 3 (0.3) | 10 (0.5) |
| Urinalysis positive | 127 (14.0) | 149 (16.3) | 276 (15.2) |
| WBC, mean (SD), /μL | 10 300 (4500) | 10 500 (4.9) | 10 400 (4700) |
| ANC, mean (SD), /μL | 4000 (2800) | 4200 (3300) | 4100 (3100) |
| PCT, ng/mL, median (IQR) | 0.2 (0.2-0.3) | 0.2 (0.2-0.3) | 0.2 (0.2-0.3) |
| SBI positive | 82 (9.0) | 88 (9.6) | 170 (9.3) |
| UTI alone | 65 (7.2) | 75 (8.3) | 140 (7.7) |
| Bacteremia alone | 8 (0.9) | 2 (0.2) | 10 (0.5) |
| Meningitis alone | 3 (0.3) | 1 (0.1) | 4 (0.2) |
| UTI and bacteremia | 3 (0.3) | 7 (0.8) | 10 (0.5) |
| Bacteremia and meningitis | 2 (0.2) | 3 (0.3) | 5 (0.3) |
| UTI and bacteremia and meningitis | 1 (0.1) | 0 | 1 (0.1) |
| SBI positive | |||
| Age ≤28 da | 36 (12.9) | 36 (13.1) | 72 (13.0) |
| UTI alone | 28 (10.0) | 29 (10.5) | 57 (10.3) |
| Bacteremia alone | 3 (1.1) | 1 (0.4) | 4 (0.7) |
| Meningitis alone | 2 (0.7) | 1 (0.4) | 3 (0.5) |
| UTI and bacteremia | 1 (0.4) | 3 (1.1) | 4 (0.7) |
| Bacteremia and meningitis | 1 (0.4) | 2 (0.7) | 3 (0.5) |
| UTI and bacteremia and meningitis | 1 (0.4) | 0 | 1 (0.2) |
| Age >28 da | 46 (7.3) | 52 (8.2) | 98 (7.7) |
| UTI alone | 37 (5.9) | 46 (7.2) | 83 (6.6) |
| Bacteremia alone | 5 (0.8) | 1 (0.2) | 6 (0.5) |
| Meningitis alone | 1 (0.2) | 0 | 1 (0.1) |
| UTI and bacteremia | 2 (0.3) | 4 (0.6) | 6 (0.5) |
| Bacteremia and meningitis | 1 (0.2) | 1 (0.2) | 2 (0.2) |
| UTI and bacteremia and meningitis | 0 | 0 | 0 |
Abbreviations: ANC, absolute neutrophil count; ED, emergency department; IQR, interquartile range; PCT, procalcitonin; SBI, serious bacterial infection; UTI, urinary tract infection; WBC, white blood cell count; YOS, Yale Observation Scale score.
SI conversion factors: To convert ANC to ×109 per liter, multiply by 0.001; WBC to ×109 per liter, multiply by 0.001.
a
Percentages are calculated out of all patients in the referenced age category (n = 280 and 275 for 28 days and younger, n = 628 and 638 for older than 28 days).