Of 1000 patients arriving at hospital with mild head injury, 1 will die, 9 will require surgery or other intervention, and about 80 will show pathological findings on CT. At least these 8% of patients will probably need in-hospital care.

Objective: To search the literature for case reports on adverse outcomes in patients with mild head injury where acute computed tomography (CT) findings had been normal. Methods: Mild head injury was defined as head trauma involving amnesia or loss of consciousness, but where neurological findings are normal on arrival at hospital (GCS 15). The scientific literature was systematically searched for case reports where an early CT was normal and the patient deteriorated within two days. In these cases, early discharge despite a normal CT head scan would have been hazardous. Results: Two prospective studies were found that investigated the safety of early CT in 3300 patients with mild head injury, as were 39 reports on adverse outcomes describing 821 patients. In addition, 52 studies containing over 62 000 patients with mild head injury were reviewed. In total, only three cases were deemed to have experienced an early adverse outcome despite a normal CT and GCS 15 on initial presentation. In another eight cases with incomplete descriptions, the interpretation was doubtful. Many reports of complications were not relevant to our question and excluded. These reports included cases with more severe head injury/not GCS 15 at presentation, complications that occurred after more than two days, or initial CT findings that were not fully normal. Conclusion: Very few cases were found where an early adverse event occurred after normal acute CT in patients with mild head injury. The strongest scientific evidence available at this time shows that a CT strategy is a safe way to triage patients for admission.

Objectives: To compare the costs of two strategies for acute management of mild head injury: inhospital observation compared with acute computed tomography (CT) and home care. Methods: Studies comparing costs for the two strategies that seem to have similar outcomes for patients were systematically reviewed. A decision tree analysis to compare the costs was also constructed, based on Swedish national costs and the risks found in a recent review on mild head injury complications. Results: No studies were found that directly measured and compared risks, benefits, and costs of the two strategies. In the four studies retrieved, involving 4126 patients, the costs for hospital observation were factual, but a model was used to evaluate costs for the CT strategy. On average, costs were one third lower with CT. Also, the decision tree analysis demonstrated that the CT strategy was one third less expensive than inhospital observation. A sensitivity analysis showed this to be valid for nearly all cases. If these calculations hold true, a change of strategy could result in annual savings of £280 000/million inhabitants. Conclusion: The CT strategy seems to cost one third less than hospital observation.M ild head injury is one of the most common reasons for hospital admission after trauma. Annually, 17 000 patients (190/100 000 inhabitants) are admitted with mild head injuries in Sweden.1 Direct costs for the acute management of mild head injury in Sweden are estimated to be £7.6 million annually, £84 000/100 000 inhabitants.2 The indirect costs could not be reliably estimated, but seem to be considerably higher than the direct costs.No uniform guidelines for the care of mild head injury are broadly accepted. Sweden and many other European countries have a longstanding tradition of managing mild head injury with inhospital observation.3-7 Some of the admitted patients receive a computed tomography (CT) scan in addition to inhospital care, around 20% in Sweden. 4 The question has been raised concerning whether all patients with mild head injury instead can be triaged for admission with an early CT scan.8 Unnecessary admissions of patients with normal CT findings might thereby be avoided, and better care provided for patients with abnormal CT findings and at higher risk for deterioration with need for surgery or more intensive care. In our recent review of complications from mild head injury we estimated that even with the CT strategy at least 8% of the patients will require inhospital care because of abnormal CT findings or complications.9 It is also possible that an additional 10% might require admission because of organisational, medical, or social reasons despite normal CT findings.The use of skull radiography to triage patients with mild head injury for admission or for CT has been discussed.10 11 In Sweden, this method is not used routinely. 4 Most evidence shows that skull radiography is less informative than CT and of limited value for the management of head injuries of a milder degree.12 13 Furthermore, skull radiogra...