Martin H Osmond, Terry P Klassen, George A Wells, Jennifer Davidson, Rhonda Correll, Kathy Boutis, Gary Joubert, Serge Gouin, Simi Khangura, Troy Turner, Francois Belanger, Norm Silver, Brett Taylor, Janet Curran, Ian G Stiell

There is uncertainty about which children with minor head injury need to undergo computed tomography (CT). We sought to prospectively validate the accuracy and potential for refinement of a previously derived decision rule, Canadian Assessment of Tomography for Childhood Head injury (CATCH), to guide CT use in children with minor head injury. This multicentre cohort study in 9 Canadian pediatric emergency departments prospectively enrolled children with blunt head trauma presenting with a Glasgow Coma Scale score of 13-15 and loss of consciousness, amnesia, disorientation, persistent vomiting or irritability. Phys icians completed standardized assessment forms before CT, including clinical predictors of the rule. The primary outcome was neurosurgical intervention and the secondary outcome was brain injury on CT. We calculated test characteristics of the rule and used recursive partitioning to further refine the rule. Of 4060 enrolled patients, 23 (0.6%) underwent neurosurgical intervention, and 197 (4.9%) had brain injury on CT. The original 7-item rule (CATCH) had sensitivities of 91.3% (95% confidence interval [CI] 72.0%-98.9%) for neurosurgical intervention and 97.5% (95% CI 94.2%-99.2%) for predicting brain injury. Adding "≥ 4 episodes of vomiting" resulted in a refined 8-item rule (CATCH2) with 100% (95% CI 85.2%-100%) sensitivity for neurosurgical intervention and 99.5% (95% CI 97.2%-100%) sensitivity for brain injury. Among children presenting to the emergency department with minor head injury, the CATCH2 rule was highly sensitive for identifying those children requiring neurosurgical intervention and those with any brain injury on CT. The CATCH2 rule should be further validated in an implementation study designed to assess its clinical impact.