BACKGROUND: A quarter of all patients presenting to emergency departments are 
children. Although there are several large, well-conducted studies on adults 
enabling accurate selection of patients with head injury at high risk for 
computed tomography scanning, no such study has derived a rule for children.
AIM: To conduct a prospective multicentre diagnostic cohort study to provide a 
rule for selection of high-risk children with head injury for computed 
tomography scanning.
DESIGN: All children presenting to the emergency departments of 10 hospitals in 
the northwest of England with any severity of head injury were recruited. A 
tailor-made proforma was used to collect data on around 40 clinical variables 
for each child. These variables were defined from a literature review, and a 
pilot study was conducted before the children's head injury algorithm for the 
prediction of important clinical events (CHALICE) study. All children who had a 
clinically significant head injury (death, need for neurosurgical intervention 
or abnormality on a computed tomography scan) were identified. Recursive 
partitioning was used to create a highly sensitive rule for the prediction of 
significant intracranial pathology.
RESULTS: 22,772 children were recruited over 2 1/2 years. 65% of these were boys 
and 56% were <5 years old. 281 children showed an abnormality on the computed 
tomography scan, 137 had a neurosurgical operation and 15 died. The CHALICE rule 
was derived with a sensitivity of 98% (95% confidence interval (CI) 96% to 100%) 
and a specificity of 87% (95% CI 86% to 87%) for the prediction of clinically 
significant head injury, and requires a computed tomography scan rate of 14%.
CONCLUSION: A highly sensitive clinical decision rule is derived for the 
identification of children who should undergo computed tomography scanning after 
head injury. This rule has the potential to improve and standardise the care of 
children presenting with head injuries. Validation of this rule in new cohorts 
of patients should now be undertaken.