TABLE 3

Model Performance

ModelaNo. ChildrenPredictors (df)LR χ2AICC-Index (95% CI)Bootstrap C-Indexb
Full183920 (45)51821210.81 (0.79–0.83)0.79
Reduced223810 (31)50924530.79 (0.77–0.81)0.77
EHR19029 (28)45223000.78 (0.76–0.80)0.76
  • AIC, Akaike Information Criterion; CI, confidence interval; c-index, concordance index; df, degrees of freedom; LR χ2, likelihood ratio χ2.

  • a Full model includes age, race, sex, composite comorbidity variable (0, 1, 2, or 3+), home smoke exposure, season, symptom duration, vomiting, PF ratio, heart and respiratory rates, systolic blood pressure, temperature, altered mental status, chest indrawing, asymmetric breath sounds, wheezing, white blood cell count, and radiographic findings (infiltrate pattern and presence of effusion). Reduced model includes age, composite comorbidity variable, chest indrawing, altered mental status, PF ratio, heart and respiratory rates, systolic blood pressure, and radiographic findings. EHR model includes age, sex, race, PF ratio, heart and respiratory rates, systolic blood pressure, temperature, and white blood cell count.

  • b To estimate expected performance in future populations, an internal bootstrap validation (500 replications with replacement) of the final models was performed.