Objective The Pediatric Emergency Care Applied Research Network (PECARN) traumatic brain injury (TBI) age-based clinical prediction rules identify children at very low risk of a significant head injury who can safely avoid CT. Our goal was to independently validate these prediction rules.

Design Cross-sectional study.

Setting Two paediatric emergency departments located in USA and in Italy.

Patients All children presenting within 24 h of a head injury with a Glasgow Coma Score of ≥14.

Intervention Assessment of PECARN TBI clinical predictors.

Main outcome measure Clinically important TBI defined as head injury resulting in death, intubation for >24 h, neurosurgery or two or more nights of hospitalisation for the management of head trauma.

Results During the study period, we included 2439 children (91% of eligible patients), of which 959 (39%) were <2 years of age and 1439 (59%) were male. Of the study patients, 373 (15%) had a CT performed, 69 (3%) had traumatic findings on their CT and 19 (0.8%) had a clinically important TBI. None of the children with a clinically important TBI were classified as very low risk by the PECARN TBI prediction rules (overall sensitivity 100%; 95% CI 83.2% to 100%, specificity 55%, 95% CI 52.5% to 56.6%, and negative predictive value 100%, 95% CI 99.6% to 100%).

Conclusions In our external validation, the age-based PECARN TBI prediction rules accurately identified children at very low risk for a clinically significant TBI and can be used to assist CT decision making for children with minor blunt head trauma.