Validating the PECARN rule to identify febrile infants at low risk of serious bacterial infections: an international validation study.

Objective: To externally validate the Paediatric Emergency Care Applied Research Network (PECARN) rule for identifying febrile infants aged <60 days at low risk of serious bacterial infections (SBIs) and assess the utility of the rule with C reactive protein (CRP) instead of procalcitonin (PCT).

Methods: Secondary analysis of data from the Management and Outcomes of Fever in Children in Europe (MOFICHE) study (12 paediatric emergency departments in eight European countries, January 2017 to April 2018) and a Swedish study (four paediatric emergency departments, January 2014 to December 2020). Previously healthy febrile infants aged ≤60 days were included. We validated the original PECARN rule in a Swedish subcohort (2018-2020) and explored an adapted version using CRP in the full Swedish and MOFICHE cohorts.

Results: The Swedish subcohort (2018-2020) included 536 febrile infants with an SBI prevalence of 11%. The original PECARN rule showed a sensitivity of 96.6% (95% CI 88.1 to 99.6), specificity of 61.9% (95% CI 57.4 to 66.3), negative predictive value (NPV) of 99.3% (95% CI 97.4 to 99.8) and positive predictive value (PPV) of 23.5% (95% CI 21.4 to 25.8). The full Swedish cohort (2014-2020) included 2237 infants and the MOFICHE cohort of 512 infants with 12% and 10% SBI prevalence, respectively. Using CRP <20 mg/L instead of PCT, the adapted PECARN rule showed a sensitivity of 97.8% and NPV of 99.4% in the Swedish cohort, and sensitivity of 92.2% with an NPV of 98.3% in the MOFICHE cohort.

Conclusions: The PECARN rule demonstrated high NPV (similar to the derivation cohort) and high potential in ruling out SBIs in two new European cohorts. The rule maintained good performance with CRP instead of PCT, supporting the potential use of CRP in settings where PCT is unavailable.