Computed tomography of the head for adult patients with minor head injury: are clinical decision rules a necessary evil?

INTRODUCTION This study aimed to evaluate compliance with and performance of the Canadian Computed Tomography Head Rule (CCHR), and its applicability to the Singapore adult population with minor head injury. METHODS We conducted a retrospective study over six months of consecutive patients who presented to the adult emergency department (ED) with minor head injury. Data on predictor variables indicated in the CCHR was collected and compliance with the CCHR was assessed by comparing the recommendations for head computed tomography (CT) to its actual usage. RESULTS In total, 349 patients satisfied the inclusion criteria. Common mechanisms of injury were falls (59.3%), motor vehicle crashes (16.9%) and assault (12.0%). 249 (71.3%) patients underwent head CT, yielding 42 (12.0%) clinically significant findings. 1 (0.3%) patient required neurosurgical intervention. According to the CCHR, head CT was recommended for 209 (59.9%) patients. Compliance with the CCHR was 71.3%. Among the noncompliant group, head CT was overperformed for 20.1% and underperformed for 8.6% of patients. Multivariate logistic regression analysis revealed that absence of retrograde amnesia (odds ratio [OR] 4.1, 95% confidence interval [CI] 1.8-9.7) was associated with noncompliance to the CCHR. Factors associated with underperformance were absence of motor vehicle crashes as a mechanism of injury (OR 6.6, 95% CI 1.2-36.3) and absence of headache (OR 10.8, 95% CI 1.3-87.4). CONCLUSION Compliance with the CCHR for adult patients with minor head injury remains low in the ED. A qualitative review of physicians' practices and patients' preferences may be carried out to evaluate reasons for noncompliance.