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    PECARN Rule for Low Risk Febrile Infants 29-60 Days Old

    Predicts risk of urinary tract infection, bacteremia, or bacterial meningitis in febrile infants age 29-60 days old.


    This calculator is not yet externally validated. While derived in infants aged 0-60 days, the creators recommend using this calculator only in infants aged 29-60 days (i.e., do not use in infants 28 days or younger), due to elevated herpes meningoencephalitis risk and and limited numbers of episodes of bacterial meningitis in that age group (see Pearls/Pitfalls and Creator Insights for details).


    Does not apply to ill-appearing infants. The rule is intended to be one-directional: it may help rule out serious bacterial infection (SBI) in patients who are “low risk”, but the converse is not true (i.e., patients who are “not low risk” by the rule do not necessarily have SBI).

    When to Use
    Why Use

    Well-appearing infants 29-60 days old, to stratify risk of SBI (defined as urinary tract infection, bacteremia, or bacterial meningitis).

    • The majority of infants younger than 60 days old are unvaccinated and have immature immune systems.

    • Infants with signs of shock or who are otherwise ill-appearing/unstable should be considered at high risk of SBI and in most cases should have blood, urine, and CSF cultures collected. This clinical prediction rule would not apply to such patients.

    • Serum procalcitonin level is required, but may not be rapidly available in all settings.

    • Most SBIs identified in the study were UTIs, so the rule may be less accurate for bacteremia and bacterial meningitis, which have much lower prevalence.

    • Infants 28 days old and younger warrant special attention, as they are at elevated risk of herpes meningoencephalitis as well as a more rapid progression of disease. The study authors recommend a full laboratory evaluation, including CSF, for those 28 days and younger.

    • In the study, three infants were misclassified as being low risk but did have SBIs (two UTI, and one Enterobacter cloacae bacteremia). All were treated appropriately based on culture results and had uneventful clinical courses.

    • As noted in the Supplement, alternative cutoffs for ANC (4,000) and procalcitonin (0.5) were studied and found to be comparable to the published cutoffs in terms of accuracy. Per the authors of the study, clinicians should consider using these cutoffs as they are easier, safer, and less confusing to use clinically, and had minimal impact on accuracy of the rule (see Creator Insights for details).

    • Physical exam alone is unreliable in ruling out SBI in febrile infants.

    • May avoid unnecessary lumbar punctures, empirical antibiotics, and hospital admissions. 

    • Helps determine disposition of some well-appearing infants who can reliably follow up with their primary pediatrician or in the ED in 24 hours and/or can be relied upon to return to the ED should a pending culture return positive.



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    Creator Insights
    Dr. Nathan Kuppermann

    From the Creator

    Why did you develop the PECARN Rule for Low Risk Febrile Infants? Was there a particular clinical experience or patient encounter that inspired you to create this tool for clinicians?

    For years, clinicians seeing young febrile infants have struggled with algorithms and criteria that attempt to stratify risk for invasive bacterial infections (i.e., bacteremia and/or bacterial meningitis) in young febrile infants. Clinicians do not want to miss infants with these infections, but they also don't want to test or over-treat infants who don't need it. Prior algorithms, however, are dated, use consensus-based thresholds for laboratory cutoffs, and do not use newer, more accurate biomarkers. 

    What pearls, pitfalls and/or tips do you have for users of the PECARN Rule for Low Risk Febrile Infants? 

    Although we derived the rule in infants age 0-60 days, the rule should not yet be used in those ≤28 days because of their HSV risk. This prediction rule is for invasive bacterial infections, not for serious viral infections. We also need larger validation numbers of febrile infants in the first month of life with bacteremia and bacterial meningitis before using the rule in that age group, and we strongly warned readers of that in the article. We are currently validating the score on another (approximately) 1,300 febrile infants.

    Also, per the data in our supplement, we are planning to implement the cutoffs of 4,000 for ANC and 0.5 for procalcitonin, as they are easier, safer and less confusing to use clinically, and we found that they had minimal impact on the accuracy of the rule. We feel that the biggest impact of this study / prediction rule is identifying low risk infants 29-60 days old on whom we may obviate lumbar punctures, empirical antibiotic administration and hospitalization. The 28-day and younger group is a higher risk group, especially those 21 days and younger. At this point, we would advocate a full laboratory evaluation, including CSF, for those 28 days and younger. Those who are 22-28 days old and found to be low risk can perhaps have a short hospitalization or prolonged ED observation after the laboratory evaluation. 

    Any other research in the pipeline that you’re particularly excited about?

    In addition to the large external validation of the PECARN Febrile Infant Prediction Rule, we are also currently using genomic data (RNA-based diagnostic technology) to distinguish between otherwise well appearing febrile infants with bacterial and non-bacterial infections presenting to EDs. The extensive viral respiratory panels are also expensive tests; we are therefore evaluating the impact of a positive viral panel on risk of invasive bacterial infection and whether it should impact our diagnostic evaluation in the ED and subsequent decision making.

    About the Creator

    Nathan Kuppermann, MD, MPH, is a professor and chair of the department of emergency medicine at UC Davis Health and School of Medicine in Sacramento, CA. He chaired the first research network in pediatric emergency medicine (the Pediatric Emergency Medicine Collaborative Research Committee of the AAP) and was the founding chair of the Pediatric Emergency Care Applied Research Network (PECARN). Dr. Kuppermann is a leading national investigator for studies focusing on infectious emergencies in children including the laboratory evaluation of young febrile children, the evaluation of children at risk of diabetic ketoacidosis-related cerebral injury, and the laboratory and radiographic evaluation of the pediatric trauma patient. He has been the lead or senior investigator on several research studies developing and validating clinical prediction rules.

    To view Dr. Nathan Kuppermann's publications, visit PubMed

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