A Prediction Model to Identify Febrile Infants ≤60 Days at Low Risk of Invasive Bacterial Infection

OBJECTIVES: To derive and internally validate a prediction model for the identification of febrile infants ≤60 days old at low probability of invasive bacterial infection (IBI). METHODS: We conducted a case-control study of febrile infants ≤60 days old who presented to the emergency departments of 11 hospitals between July 1, 2011 and June 30, 2016. Infants with IBI, defined by growth of a pathogen in blood (bacteremia) and/or cerebrospinal fluid (bacterial meningitis), were matched by hospital and date of visit to 2 control patients without IBI. Ill-appearing infants and those with complex chronic conditions were excluded. Predictors of IBI were identified with multiple logistic regression and internally validated with 10-fold cross-validation, and an IBI score was calculated. RESULTS: We included 181 infants with IBI (155 [85.6%] with bacteremia without meningitis and 26 [14.4%] with bacterial meningitis) and 362 control patients. Twenty-three infants with IBI (12.7%) and 138 control patients (38.1%) had fever by history only. Four predictors of IBI were identified (area under the curve 0.83 [95% confidence interval (CI): 0.79–0.86]) and incorporated into an IBI score: age CONCLUSIONS: Infants ≤60 days old with fever by history only, a normal urinalysis result, and an absolute neutrophil count