Written by Kimiko Dunbar
Spoon Feed
A newly derived decision rule with liberalized ANC, CRP, and temperature thresholds for infants 8-60 days improved specificity from 50% to 84%, while maintaining 100% sensitivity.
No procal? No problem
In the absence of procalcitonin testing, AAP guidelines recommend using thresholds of ANC ≤ 5200/mm3, CRP ≤ 20 mg/L, and temperature ≤38.5°C to determine low risk of IBI in febrile infants 22-60 days old. While these cutoffs are 100% sensitive, specificity is lacking at 35-48%. This study aimed to optimize the identification of febrile young infants at low risk for IBIs in the event that procalcitonin is unavailable. This was a secondary analysis of prospectively collected data from 1,987 infants ≤60 days old evaluated in a pediatric emergency department. Using classification and regression tree analysis, their derived decision tool using CRP ≤22.2 mg/L, temperature ≤39.0°C, and ANC ≤4500/mm³ improved specificity (83.8% vs. 50.7%) while maintaining 100% sensitivity. In this cohort, the derived thresholds reclassified 644 infants (32%) as low-risk who likely did not need LP, empiric antibiotics, or admission. Contrary to AAP guidelines, this study did not find age to be a predictor of IBI, suggesting that our age based approach to risk stratification could be liberalized. This study was conducted at a single-center large academic institution and is limited by lack of external validation.
How will this change my practice?
There is a lot of potential here, but a bit more work needs to be done before it changes my practice – namely expanding this to multiple sites/external validation. Febrile infants are tricky. Since fever might be the only sign of IBI, we are dependent on guidelines to risk stratify and guide work-up and management. I’m not ready to forego extended work-up in a patient with fever >38.5 but <39.0 just yet, but I can imagine how these data may be helpful for borderline cases where it’s difficult to rely on guidelines – i.e. febrile 59 day old infant or situations where CSF cannot be obtained, etc.
Source
Optimizing Management of Febrile Young Infants Without Serum Procalcitonin. Pediatrics. 2025 Feb 1;155(2):e2024068200. doi: 10.1542/peds.2024-068200. PMID: 39749980
