Febrile Young Infants With Altered Urinalysis at Low Risk for Invasive Bacterial Infection. A Spanish Pediatric Emergency Research Network's Study

Background: Urinary tract infection (UTI) is the most common serious bacterial infection (SBI) in infants younger than 90 days of age. Many physicians admit infants younger than 90 days old because of their greater risk of developing invasive bacterial infections (IBIs), secondary to UTI. The primary objective of this study was to design a prediction model to identify febrile infants younger than 90 days old with an altered urinalysis who were at low risk for IBI and suitable for outpatient management Methods: Prospective multicenter study included 19 hospitals that are members of the Spanish Pediatric Emergency Research Group of the Spanish Society of Pediatric Emergencies. Febrile infants younger than 90 days old with altered urinalysis were included. Results: A total of 766 (22.5%) infants with altered urine dipstick were analyzed. Fifty (6.5%) of them developed IBI, 39 (78.0%) secondary to UTI. Patients were at low risk for IBI if they were well appearing at arrival to the emergency department, were older than 21 days and had procalcitonin and C-reactive protein (CRP) blood values lower than 0.5 ng/mL and 20 mg/L, respectively. These factors were used to create a prediction model for IBI secondary to UTI, with a sensitivity of 100% (95% CI: 89.3-100) and a negative predictive value of 100% (95% CI: 97.5-100). Conclusions: We have derived a highly accurate prediction model for IBI in febrile infants with altered urinalysis. Given these results, outpatient management might be suitable for 1 of each 4 infants diagnosed, with a considerable improvement in resource utilization.