The Canadian CT head rule for patients with minor head injury

Background There is much controversy about the use of computed tomography ( CT) for patients with minor head injury. We aimed to develop a highly sensi tive clinical decision rule for use of CT in patients with minor head injur ies. Methods We carried out this prospective cohort study in the emergency depar tments of ten large Canadian hospitals and included consecutive adults who presented with a Glasgow Coma Scale (GCS) score of 13-15 after head injury. We did standardised clinical assessments before the CT scan. The main outc ome measures were need for neurological intervention and clinically importa nt brain injury on CT. Findings The 3121 patients had the following characteristics: mean age 38.7 years); GCS scores of 13 (3.5%), 14 (16.7%), 15 (79.8%); 8% had clinically important brain injury; and 1% required neurological intervention. We deri ved a CT head rule which consists of five high-risk factors (failure to rea ch GCS of 15 within 2 h, suspected open skull fracture, any sign of basal s kull fracture, vomiting greater than or equal to2 episodes, or age greater than or equal to 65 years) and two additional medium-risk factors (amnesia before impact greater than or equal to 30 min and dangerous mechanism of in jury). The high-risk factors were 100% sensitive (95% CI 92-100%) for predi cting need for neurological intervention, and would require only 32% of pat ients to undergo CT. The medium-risk factors were 98.4% sensitive (95% CI 9 6-99%) and 49.6% specific for predicting clinically important brain injury, and would require only 54% of patients to undergo CT. Interpretation We have developed the Canadian CT Head Rule, a highly sensit ive decision rule for use of CT. This rule has the potential to significant ly standardise and improve the emergency management of patients with minor head injury.