Prediction Rule to Identify Febrile Infants 61-90 Days at Low Risk for Invasive Bacterial Infections.

Area of Science:

• Pediatric Emergency Medicine
• Infectious Diseases
• Clinical Epidemiology

Background:

• Febrile infants aged 61-90 days pose a diagnostic challenge due to the risk of invasive bacterial infections (IBIs).
• Accurate identification of low-risk infants is crucial to avoid unnecessary antibiotic exposure and hospitalizations.

Purpose of the Study:

• To develop and validate clinical prediction rules for identifying febrile infants (61-90 days) at low risk of IBIs.
• To assess the utility of procalcitonin (PCT) and absolute neutrophil count (ANC) in risk stratification.

Main Methods:

• Retrospective analysis of data from 4952 infants across 17 PECARN emergency departments.
• Recursive partitioning with 10-fold cross-validation to derive prediction rules using age, temperature, urinalysis, and ANC.
• Evaluation of PCT as an additional predictor in a subset of infants.

Main Results:

• The primary rule identified low-risk infants with negative urinalysis and temperature <= 38.9°C (Sensitivity: 86.0%).
• In a subset with PCT and ANC, a rule using PCT <= 0.24 ng/mL and ANC <= 10,710 cells/mm³ achieved 100.0% sensitivity for IBI detection.
• Two IBIs (0.2%) with bacterial meningitis were identified in the PCT/ANC subset.

Conclusions:

• Two accurate clinical prediction rules were derived to identify febrile infants (61-90 days) at low risk for IBIs.
• Prospective validation of these rules is necessary before clinical implementation.