Accuracy of Canadian CT head rule in predicting positive findings on CT of the head of patients after mild head injury in a large trauma centre in Saudi Arabia

BACKGROUND: Investigation of unjustified computed tomography (CT) scan in patients with minor head injury is lacking in Saudi Arabia. The purpose of the study was to evaluate the compliance and effectiveness of the Canadian computed tomography head rule (CCHR) in our emergency department (ED) and trauma centre and also to reduce the number of unjustified CT studies of the head in the centre. METHODS: A retrospective study of 368 ED patients with minor head injury was conducted. Patients who underwent CT scan between July 2010 and June 2011 were selected from the ED head trauma registry by systematic randomisation. The CCHR was retrospectively applied on the patients' charts to calculate the prevalence of unjustified head CT scans. A separate survey was conducted to evaluate three emergency physicians' level of awareness about the CCHR and their ability to determine the necessity of CT scans with various clinical scenarios of head injury. RESULTS: The prevalence of unjustified CT scans as per the CCHR was 61.8% (95% confidence interval (CI) 56.5-66.9%). Approximately 5% of the sample had positive CT findings with 95% CI 2.9-7.6%. The CCHR correctly identified 12 cases with positive CT findings with 66.67% sensitivity. Only 24 (6.7%) had Glasgow coma scale scores less than 15 (13/14). The Glasgow coma scale correctly identified only two cases with positive CT findings with 11.11% sensitivity. The percentage of skull fracture (0.9% vs 5%, P=0.030) was significantly lower in patients with unjustified CT scans than in patients with clinically justified CT scans. There was fair to substantial agreement between the ED physicians and the CCHR (κ=35-61%). Two ED physicians identified all cases of justified CT scan with 100% sensitivity (95% CI 71.51-100%). CONCLUSION: The level of education regarding the CCHR was found to be optimal among emergency physicians using a case-based scenario survey. The CCHR was found to have a poor compliance potential in the busy ED of our trauma centre and the prevalence of unjustified cranial CT scans remained high.