No abstract

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 ,21 days (1 point), highest temperature recorded in the emergency department 38.0-38.4°C (2 points) or $38.5°C (4 points), absolute neutrophil count $5185 cells per mL (2 points), and abnormal urinalysis results (3 points). The sensitivity and specificity of a score $2 were 98.8% (95% CI: 95.7%-99.9%) and 31.3% (95% CI: 26.3%-36.6%), respectively. All 26 infants with meningitis had scores $2. CONCLUSIONS: Infants #60 days old with fever by history only, a normal urinalysis result, and an absolute neutrophil count ,5185 cells per mL have a low probability of IBI. WHAT'S KNOWN ON THIS SUBJECT: Commonly used risk-stratification criteria for febrile infants were either developed .2 decades ago in studies that included relatively few infants with bacteremia and/or bacterial meningitis or include procalcitonin, which is not readily available in some hospitals. WHAT THIS STUDY ADDS: A newly derived score is highly sensitive for the identification of non-ill-appearing febrile infants #60 days old with invasive bacterial infection. Infants with fever by history only, normal urinalysis results, and an absolute neutrophil count ,5185 cells per mL had a low probability of infection.