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Febrile Neonates Under 28 Days – Is PECARN Rule Safe?

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Written by Caitlin Nicholson

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In a large international cohort of well-appearing febrile infants ≤28 days old, the updated PECARN rule had high sensitivity and negative predictive value for invasive bacterial infection, with no missed cases of bacterial meningitis, supporting selective avoidance of routine lumbar puncture in low-risk neonates.

Don’t miss Dr. Josh Belfer’s interview with lead author Dr. Burstein and senior author Dr. Kuppermann on his blog HipPEMcrates.com.

PECARN keeps pushing the envelope for safer, smarter pediatric emergency care.
This study evaluated the diagnostic performance of the updated PECARN prediction rule for identifying febrile infants ≤ 28 days old at low risk for invasive bacterial infections (IBIs), specifically bacteremia and bacterial meningitis. Using a pooled analysis of four prospective cohort studies from pediatric emergency departments in six countries, investigators included previously healthy, full-term, non-ill-appearing neonates with fever ≥ 38.0°C who underwent blood, urine, and serum testing. Infants were classified as low risk if they had a negative urinalysis, procalcitonin ≤ 0.5 ng/mL, and an absolute neutrophil count ≤ 4000/mm³. Meta-analytic methods were used to calculate diagnostic accuracy across cohorts.

Among 1,537 infants, 4.5% had any IBI, and 0.7% had bacterial meningitis. The PECARN rule demonstrated high sensitivity (94.2%) and an excellent negative predictive value (99.4%) for IBIs, though specificity was modest (41.6%). No cases of bacterial meningitis were misclassified as low risk, suggesting the rule is highly reliable for ruling out meningitis in this population. Approximately 41% of infants met low-risk criteria, of which 4 were found to have IBI (bacteremia). Limitations include restriction to pediatric ED settings, reliance on rapid procalcitonin availability, lack of representation from low- and middle-income countries, and the absence of herpes simplex virus risk assessment. 

How will this change my practice?
There is persistent tension between avoiding catastrophic missed infections and minimizing low-value, invasive care in a population whose risk is often clinically indistinguishable at presentation. Although the updated PECARN rule offers reassuring evidence—most notably, the absence of missed bacterial meningitis among low-risk infants—it is unlikely to prompt an immediate change in my practice, and existing guidelines will continue to anchor decision-making given the potential severity of a missed diagnosis. Instead, these findings better inform shared discussions with families and support a cautious, incremental shift toward individualized, risk-based evaluation in select well-appearing neonates, particularly those closer to 22–28 days of age with reliable follow-up.

Another Spoonful
Get it straight from the source. Don’t miss Dr. Josh Belfer’s interview with lead author Dr. Burstein and senior author Dr. Kuppermann on his blog HipPEMcrates.com.

Source
Prediction of Bacteremia and Bacterial Meningitis Among Febrile Infants Aged 28 Days or Younger. JAMA. 2025 Dec 8:e2521454. doi: 10.1001/jama.2025.21454. Epub ahead of print. PMID: 41359314; PMCID: PMC12687207.

View JournalFeed Critical Appraisal

Critical Appraisal

Title: Prediction of Bacteremia and Bacterial Meningitis Among Febrile Infants Aged 28 Days or Younger.
Background: Fever in infants under 28 days can indicate serious bacterial infections like bacteremia or meningitis. Current guidelines recommend lumbar punctures for all febrile infants, but prediction rules may help identify those at low risk.
Study Question: How accurately does a clinical prediction rule identify febrile infants at low risk for bacteremia and/or bacterial meningitis?
Study Design: Pooled analysis of 4 prospective cohort studies.
Population: 1537 febrile infants aged 28 days or younger from 6 countries.
Intervention: Classification as low risk based on urinalysis, procalcitonin, and absolute neutrophil count.
Comparison: Not applicable
Primary Outcome: Diagnostic accuracy of the PECARN prediction rule for invasive bacterial infections.
Secondary Outcomes: None reported
Key Statistics: Meta-analytic methods, sensitivity, specificity, positive and negative predictive values.
Results: Sensitivity 94.2% (95% CI, 85.6%-97.8%), specificity 41.6% (95% CI, 36.7%-46.7%), PPV 6.9% (95% CI, 4.8%-9.9%), NPV 99.4% (95% CI, 98.1%-99.8%).
Risk of Bias - AMSTAR 2:
  • Overall Bias: AMSTAR 2: 0 critical flaws, indicating low risk of bias.
Take Home: The PECARN prediction rule is highly sensitive for identifying low-risk febrile infants, potentially reducing unnecessary lumbar punctures.
This critical appraisal is generated using a structured framework applied to the full text of the original article and is presented separately from the physician’s commentary.

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