New Decision Rule Identifies Kids With Minor Head Trauma Who Need CT

Fran Lowry

February 12, 2010

February 12, 2010 — A new decision rule can identify children with minor head injury who need to undergo computed tomography (CT), thereby reducing the number of scans and saving children from unnecessary exposure to ionizing radiation, according to a new study published in the February 8 issue of the Canadian Medical Association Journal.

"Over the past decade the use of CT for minor head injury has become increasingly common, while its diagnostic yield has remained low," write Martin H. Osmond, MD, from the University of Ottawa, Canada, and colleagues for the Pediatric Emergency Research Canada Head Injury Study Group. "The increased use of CT adds substantially to health care costs and exposes a large number of children each year to potentially harmful effects of ionizing radiation."

At this time there are no widely accepted, evidence-based guidelines on the use of CT for children with minor head injury, the authors write. The aim of this prospective cohort study was to develop a sensitive clinical decision rule to guide physicians in determining whether a child with minor head trauma should receive a CT scan.

The study was conducted at 10 Canadian pediatric teaching hospitals and enrolled 3866 consecutive children aged up to 16 years (mean age, 9.2 years) who presented to the emergency department after sustaining an acute minor head injury within the past 24 hours.

A minor injury was defined as blunt trauma to the head resulting in witnessed loss of consciousness, definite amnesia, witnessed disorientation, persistent vomiting (2 or more distinct episodes of vomiting 15 minutes apart) or persistent irritability in the emergency department (for children younger than 2 years), and a score of 13 to 15 on the Glasgow Coma Scale.

After initial examination, the treating physician determined whether the patient should undergo CT of the head. The main outcome measures were need for neurologic intervention and presence of brain injury, as determined by CT.

Among the 3866 patients, 95 (2.5%) had a score of 13 on the Glasgow Coma Scale, 282 (7.3%) had a score of 14, and 3489 (90.2%) had a score of 15.

The CT scan revealed that 159 patients (4.1%) had a brain injury and 24 (0.6%) required neurologic intervention.

Results Used to Develop CATCH Rule

From these results, the investigators developed a decision rule for when to perform a CT of the head, which they called the Canadian Assessment of Tomography for Childhood Head injury (CATCH) rule.

This rule states that CT of the head is required only for children with minor head injury and any one of the following findings, which they divided into high risk, meaning the need for neurologic intervention, and medium risk, meaning brain injury on CT scan.

  • High risk

    1. Failure to reach a score of 15 on the Glasgow Coma Scale within 2 hours

    2. Suspected open or depressed skull fracture

    3. History of worsening headache

    4. Irritability on examination

  • Medium risk

    1. Any sign of basal skull fracture

    2. Large, boggy hematoma of the scalp

    3. Dangerous mechanism of injury (eg, motor vehicle crash, fall from elevation > 3 feet [91 cm] or 5 stairs, fall from bicycle with no helmet)

The high-risk factors were 100.0% sensitive (95% confidence interval [CI], 86.2% - 100.0%) for predicting the need for neurologic intervention and would require that 30.2% of patients undergo CT.

The medium-risk factors were 98.1% sensitive (95% CI, 94.6% - 99.4%) for the prediction of brain injury by CT and would require that 52.0% of patients undergo CT, the study authors report.

"We derived the CATCH rule according to strict methodologic standards and using a large sample of patients," the authors write. "Nevertheless, we intend to prospectively and explicitly validate the rule at multiple sites."

The authors list potential limitations of their study. Not all enrolled children with minor head injury underwent CT, not all children with minor head injury seen at the study sites were enrolled in the study, and relatively few children younger than 2 years were enrolled. "Further prospective study of this subgroup is required, as children under two years of age may have more subtle presentations of head injury than older children," they write.

The authors conclude that the CATCH rule has the potential to standardize the need for CT, as well as to reduce the number of CT scans performed on children with minor head injury. "Further studies are required to prospectively validate this rule in other pediatric cohorts."

The study was supported by the Canadian Institutes of Health Research, the Emergency Health Services Branch of the Ontario Ministry of Health and Long-Term Care, and the Alberta Children's Hospital Foundation. The authors have disclosed no relevant financial relationships.

CMAJ. Published online February 8, 2010.

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