Efficacy of Canadian computed tomography head rule in predicting the need for a computed-axial tomography scans among patients with suspected head injuries

Context: The use of imaging modalities is crucial in the diagnostic field of critical medicine. However, the ethical and economic use of these techniques has become a major concern especially in resource-poor settings. The Canadian computed tomography Head Rule (CCHR) is being increasingly used all over the world to evaluate the necessity of a Computer-assisted Tomography (CT) scan in patients with suspected head injury.

Aim: The aim of the current study is to evaluate the efficacy of CCHR to predict the occurrence of head injury, as evidenced radiologically by a CT Head, at a government tertiary care clinical setting in south India.

Setting and design: The design was that of a hospital-based cross-sectional survey conducted at the Medical College Hospital, Thiruvananthapuram (Kerala, India).

Materials and methods: The study subjects were patients with suspected head injury evaluated at the Surgical Casualty Department of the study setting. Fifty consecutive patients with suspected head injury were enrolled in the study.

Statistical analysis: The Chi-square test was used to assess the statistical significance of association between the outcome variable and the exposure characteristics. The diagnostic ability of the Glasgow Coma Scale (GCS) and CCHR were expressed in terms of sensitivity and specificity by considering CT diagnosed Head injury as the gold standard diagnostic tool.

Results: Clinical manifestations as measured by a GCS score < 13 failed to significantly predict a head injury in the CT scan. However, the same became statistically significant when the CCHR was added to the GCS score as a predictor (P value < 0.001). The sensitivity of the tool in predicting a head injury rose from 23.3 to 96.7%.

Conclusion: The current study suggested that the CCHR could act as an excellent decision rule to indicate the need of a CT scan. The need of a decision rule was warranted in the context of the growth of newer diagnostic imaging facilities in India.