Accuracy of PECARN rule for predicting serious bacterial infection in infants with fever without a source

Objective: To validate the Febrile Infant Working Group of the Pediatric Emergency Care Applied Research Network (PECARN) clinical prediction rule on an independent cohort of infants with fever without a source (FWS).

Design: Secondary analysis of a prospective registry.

Setting: Paediatric emergency department of a tertiary teaching hospital.

Patients: Infants ≤60 days old with FWS between 2007 and 2018.

Main outcome measures: Prevalence of serious bacterial infection (SBI) and invasive bacterial infection (IBI) in low-risk infants according to the PECARN rule.

Results: Among the 1247 infants included, 256 were diagnosed with an SBI (20.5%), including 38 IBIs (3.1%). Overall, 576 infants (46.0%; 95% CI 43.4% to 49.0%) would have been classified as low risk of SBI by the PECARN rule. Of them, 26 had an SBI (4.5%), including 5 with an IBI (2 (0.8%) diagnosed with bacterial meningitis). Sensitivity and specificity of the PECARN rule were 89.8% (95% CI 85.5% to 93.0%) and 55.5% (95% CI 52.4% to 58.6%) for SBI, with an area under the curve of 0.726 (95% CI 0.702 to 0.750). Its sensitivity to identify SBIs was 88.6% (95% CI 82.0% to 92.9%) among infants with a <6-hour history of fever (54.9% of the infants included).

Conclusions: The PECARN clinical rule for identifying SBI performed less well in our population than in the original study. This clinical rule should be applied cautiously in young infants with a short history of fever.