CT for mild head injury shines in triage

Scan first, ask questions later is the message from a multicenter study examining the merits of immediate CT in triage of mild head injury patients. Data collected from almost 40 hospitals in Sweden show that routine CT scanning is more cost-effective than a policy of admit and observe for this patient group, and it leads to a comparable clinical outcome.

The study was initiated five years ago, when interest in CT was growing but evidence on its use for the acute management of mild head injury was virtually nonexistent, said Dr. Jean-Luc af Geijerstam, a researcher at the clinical epidemiology unit of Karolinska University Hospital in Stockholm. Current policy in Sweden is to admit patients with mild head injury for observation. Around one-fifth of these patients will also receive head CT.

Af Geijerstam and colleagues studied data on 2602 patients six years of age and older presenting with mild head injury at one of 39 hospital emergency departments in Sweden between May 2001 and January 2004. Just over half of the patients were assigned randomly to immediate CT, while the remainder were admitted for observation and treated according to local guidelines. No record was kept of the make or model of imaging equipment used.

All but 90 patients (3.5%) received their allocated treatment; 24 patients in the CT group failed to receive a scan, and 66 patients in the observation group were not admitted. Some additional investigations were also carried out. An extra 117 of patients randomized for CT were admitted for observation, while 111 of the observation group underwent head CT.

Follow-up showed that 275 (21.4%) of the immediate CT group had not recovered completely three months after injury, compared with 300 (24.2%) of the observation group. Incidence of mortality and more severe loss of function were similar between the two groups. No patients with normal findings on immediate CT suffered complications later. The study appeared online Aug. 8 for the British Medical Journal.

The team calculated cost per patient during the acute stage and complications to be $582 in the CT group and $854 in the observation group. Total costs per patient after three months came in at $905 and $1152, respectively.

The study surprised many emergency physicians who had expected problems implementing the immediate CT policy, af Geijerstam said.

"There was a common misconception that this strategy would lead to an enormous amount of additional head CT scans," he said. "In fact, most patients presenting at the emergency department with head trauma do not have a mild head injury, they have a minimal head injury, which requires neither observation nor CT scanning."

Hospitals wishing to extend the role of CT in their triage protocols need to consider whether they have adequate scanner capacity, said Prof. Adrian Dixon, warden of the U.K. Royal College of Radiologists (RCR). This is especially true in the U.K. where government funding has been channeled toward a relatively small number of state-of-the-art machines.

Practitioners should also consider the slight risk to patients from increased exposure to ionizing radiation, Dixon said. The type of CT scanner used is unlikely to make any difference to doctors' diagnostic confidence in this setting.

The RCR currently recommends a number of situations in which patients presenting with mild head injury should be referred for CT. These include suspected fracture, retrograde amnesia greater than 30 minutes, and seizure. The RCR's guidelines are used widely and have been cleared with trauma surgeons, Dixon said.

"But as we speak, the threshold for doing CT is going down and down and down," he said.

The Swedish study's findings are being used to update a report from the Swedish Council on Technology Assessment in Healthcare on the use of CT in acute head trauma management. The forthcoming report will also consider drawbacks associated with CT, such as increased radiation dose, af Geijerstam said.

For more information from the Diagnostic Imaging archives:

Soaring CT use may prompt need for long-term dose monitoring

64-slice CT passes pediatric safety tests

64-slice experience bolsters head and neck expertise

Guidelines for minor head trauma CT fall short