TABLE 1.
Demographic and Clinical Characteristics of Case Patients With IBI and Matched Control Patients
| Case Patients With IBI, n = 181 | Control Patients, n = 362 | Pa,b | |
|---|---|---|---|
| Demographics | |||
| Age, d, median (IQR) | 28 (16–43) | 35.5 (23–47) | <.001 |
| Female sex, n (%) | 80 (44.2) | 161 (44.5) | .95 |
| History, n of N (%) | |||
| Prematurityc | 13 of 177 (7.3) | 20 of 339 (5.9) | .52 |
| Duration of fever ≤24 hd | 141 of 153 (92.2) | 288 of 309 (93.2) | .68 |
| Household sick contactse | 47 of 146 (32.2) | 141 of 290 (48.6) | .001 |
| Vital signs, median (IQR) | |||
| Triage temperature, °C | 38.4 (38.0–38.9) | 38.0 (37.5–38.4) | <.001 |
| Highest ED temperature, °C | 38.6 (38.2–39.0) | 38.1 (37.6–38.5) | <.001 |
| Triage HR | 177 (160–190) | 164 (152–180) | <.001 |
| Triage RR | 44 (38–56) | 44 (36–52) | .14 |
| Physical examination, n of N (%) | |||
| URI symptoms or signsf,g | 41 of 172 (23.8) | 167 of 342 (48.8) | <.001 |
| Bronchiolitish | 5 of 181 (2.8) | 21 of 362 (5.8) | .12 |
| Laboratory | |||
| Abnormal urinalysis, n of N (%)i,j | 90 of 171 (52.6) | 42 of 337 (12.5) | <.001 |
| WBC, cells per μL, median (IQR) | 11 600 (8200–15 300) | 10 000 (7700–13 000) | .001 |
| ANC, cells per μL, median (IQR) | 6322 (4119–9535) | 3524 (2056–5358) | <.001 |
HR, heart rate; RR, respiratory rate.
Unadjusted comparisons between case patients and control patients used the Mann-Whitney U test for continuous variables and the χ2 test for categorical variables.
Characteristics with P ≤ .10 were considered for inclusion in the prediction model.
Four case patients and 23 control patients were missing gestational age.
Twenty-eight case patients and 53 control patients were missing documentation of duration of fever.
Thirty-five case patients and 72 control patients were missing documentation of household sick contacts.
Nine case patients and 20 control patients were missing documentation of URI symptoms or signs.
URI symptoms or signs (eg, congestion, rhinorrhea, and cough) as documented in the history or on ED physical examination.
Signs of bronchiolitis (eg, rales, wheeze, and coarse breath sounds) as documented on ED physical examination.
Eleven case patients and 25 control patients were missing urinalysis.
Urine dipstick with positive leukocyte esterase or positive nitrites or urine microscopy with >5 WBCs per high-power field or >5 WBCs per mm3 on enhanced urinalysis.