Canadian CT Head Rule
The article: “Clinical criteria to prevent unnecessary diagnostic testing in the emergency department patients with head trauma.” Stiell IG, Wells GA, Vandemheen K. et al. Lancet. 2001;357:1391-1396
The Idea: To establish a clinical decision tool to assist in ruling out clinically important brain injury in minor head trauma in the emergency department.
The Study: A prospective cohort study enrolling 3121 adult patients in 10 large Canadian emergency departments. Patients must have had a GCS of 13 or greater within 24 hours of after blunt head trauma resulted in witnessed loss of consciousness, amnesia, or disorientation. The outcome measures were the need for neurological intervention and clinically important brain injury on CT. 44 variable were assessed and patients either received a CT head or a follow up phone call at 14 days to assess for brain injury. By logistic regression analysis and recursive partitioning analysis, the list was boiled down to 5 high-risk criteria (for neurosurgical intervention) and 2 medium-risk criteria (for brain injury on CT).
The Findings: The Canadian CT Head Rule demonstrated a 100% sensitivity (95% CI 92–100%) of the high-risk criteria in predicting need for neurosurgical intervention, and would require only 32% of patients to undergo CT. The medium-risk factors were 98.4% sensitive (95% CI 96–99%) and 49.6% specific for predicting clinically important brain injury, and would require only 54% of patients to undergo CT.
The Takeaway: The Canadian CT Head Rule is a useful tool to rule out clinically significant injury and prevent unnecessary scans. Remember, they must have had witnessed loss of consciousness, amnesia, or disorientation to even be included in the study, so think twice before you auto-order a CT head on every patient with head trauma and LOC.