SGEM#296: She’s Got the Fever but Does She Need an LP, Antibiotics or an Admission?

Date: June 14th, 2020 Guest Skeptic: Dr. Dennis Ren is a Pediatric Emergency Medicine fellow at Children’s National Hospital in Washington, DC. Reference: Kuppermann et al. A Clinical Prediction Rule to Identify Febrile Infants 60 Days and Younger at Low Risk for Serious Bacterial Infections. JAMA Pediatr. 2019. Case: A 5-week-old full term female presents to the Emergency Department (ED) for fever with rectal temp of 100.6F (38.1C). Her mother states that she has been fussier today. She also seems “congested” and is not feeding as well. She continues to have the usual number of wet diapers. The mother is worried about her sick baby. She wants to know if they will need a spinal tap, be placed on antibiotics or will need to be admitted to the hospital? Background: Fever without source in infants less than three months old represents a significant diagnostic dilemma for clinicians. Several criteria have been developed previously, including the Rochester (Jaskiewicz et al 1994), Boston (Baskin et al 1992) and Philadelphia (Baker et al 1993) criteria to help clinicians stratify the risk of serious bacterial infections (SBI). Febrile infants commonly present to the emergency department. It is estimated 8-13% may have SBI that may include urinary tract infections, bacteremia, and bacterial meningitis. It is difficult to identify which infants have SBI by clinical examination alone. There are serious consequences from missed SBI. Workup for SBI may include lumbar puncture, antibiotics, and hospitalization. These criteria (Rochester, Boston and Philadelphia) could be considered out of date in our current era of vaccinations. We covered a new protocol called the Step-by-Step approach on SGEM#171. The “Step-by-Step”rule combined both clinical factors and laboratory factors in febrile infants aged 22 to 90 days. It had a sensitivity of 98.9% to detect all SBIs. The SGEM Bottom Line #171: “If you have availability of serum procalcitonin measurement in a clinically-relevant time frame, the Step-by-Step approach to fever without source in infants 90 days old or younger is better than using the Rochester criteria or Lab-score methods. With the caveat that you should be careful with infants between 22-28 days old or those who present within two hours of fever onset.” It is important to balance the consequences of missing an SBI with performing unnecessary procedures (lumbar punctures), exposing infants to antibiotics, and prolonging hospital stay. The new study proposes a novel way of identifying low risk febrile infants 29-60 days based on three objective lab criteria. Clinical Question: Can a clinical prediction rule (tool) using laboratory data identify febrile infants under 60 days of age who are at low risk for serious bacterial infection (urinary tract infection, bacteremia, and bacterial meningitis) and reduce unnecessary lumbar punctures, antibiotic exposure, and hospitalization? Reference: Kuppermann et al. A Clinical Prediction Rule to Identify Febrile Infants 60 Days and Younger at Low Risk for Serious Bacterial Infections. JAMA Pediatr. 2019. Population: Febrile infants <60 days of age who look good and whose blood cultures were obtained to rule out SBI (fever was a rectal temperature of at least 38C) Excluded: Infants who looked critically ill, had antibiotics in the previous 48 hours, history of prematurity (≤36 weeks’ gestation), pre-existing medical conditions, indwelling devices or soft tissue infections. Intervention: Derivation and validation of accurate clinical prediction rule (tool) for infants at low risk of SBI using a negative urinalysis, ANC <4,090/uL, and procalcitonin 1.71 ng/ml or less Comparison: Pre-existing algorithms combining subjective clinical findings and lab markers Outcome: Accuracy of the prediction rule to identify infants at low risk for SBI (sensitivity, specificity, negative prediction value and negative likelihood ratio).