A substantial percentage of children who get CT scans after apparently minor head trauma do not need them, and as a result are put at increased risk of cancer due to radiation exposure. To cut this risk, two UC Davis emergency department physicians assisted in the development of guidelines aimed at helping doctors decide when to order, or not order, such scans.

The guidelines grew out of the analysis of the records of more than 42,000 children with head trauma. A national team — including UC Davis’ Nathan Kuppermann and James Holmes — did the work. The study, with Kuppermann as lead author, is posted online, lancet.com, and is due to appear in an upcoming print edition of The Lancet medical journal.

The study includes data collected at 25 hospitals from children who were evaluated for the possibility of serious brain injury following trauma to the head. Researchers found that one in five children over the age of 2 and nearly one-quarter of those under 2 who received CT scans following head trauma did not need them because they were at very low risk of having serious brain injuries. In these low-risk children, the risk of developing cancer due to radiation exposure outweighed the risk of serious brain injury.

“When you have a sample size this large, it is easier to get your hands on the truth,” said Kuppermann, professor and chair of emergency medicine, and a professor of pediatrics at UC Davis Children’s Hospital. “We think our investigation provides the best available evidence regarding the use of CT scans in children with head trauma, and it indicates that CT use can be safely reduced by eliminating its application in those children who are at very low risk of serious brain injuries.”

As part of the study, Kuppermann and his colleagues developed a set of rules for identifying low-risk patients who would not need CTs. The “prediction rules” for children under 2 and for those 2 and older depend on the presence or absence of various symptoms and circumstances, including the way the injury was sustained, a history of loss of consciousness, neurological status at the time of evaluation and clinical evidence of skull fracture for both age groups. The use of CT in patients who do not fall into the low-risk group identified by the prediction rules will depend on other factors, such as the physician’s experience, the severity and number of symptoms, and other factors.

The Centers for Disease Control estimates that 435,000 children under 14 visit emergency rooms every year to be evaluated for traumatic brain injury, or TBI. Not all head trauma results in a TBI. The severity of a brain injury may range from mild, causing brief change in mental status or consciousness, to severe, causing permanent symptoms and irreversible damage.

For years, studies have suggested that CT scans were being overused to rule out traumatic brain injuries. However, those studies were considered too small to be sufficiently accurate and not precise enough to be widely applicable to a general population. The sheer size of the Lancet study, and the fact that the investigators created the accurate prediction rules with one large group of children with head trauma and then tested the rules on another large but separate group to demonstrate their validity, allows physicians to have confidence in the results. The researchers emphasized, however, that the rules are not intended to replace clinical judgment.

“We’re arming the clinician with the best available evidence so that they can make the best decisions,” said Holmes, professor of emergency medicine in the UC Davis School of Medicine and a co-author of the report. “There certainly are instances when the risks of radiation are worth it, such as in cases of blunt head trauma which result in changes in neurological status or clinical evidence of skull fractures. However, clinicians need reliable data to help them make those judgment calls when it is not clear whether or not a patient needs a CT. Until now, physicians haven’t had data based on large and validated research.”

The study comes on the heels of an article published in late August by The New England Journal of Medicine that showed that at least 4 million Americans under age 65 are exposed to high doses of radiation each year from medical imaging tests, with CT scans accounting for almost one half of the total radiation dose. About 10 percent of those get more than the maximum annual exposure allowed for nuclear power plant employees or anyone else who works with radioactive material.

Studies show that exposure to radiation increases the risk of cancer. Radiation exposure to the brain of developing children is of particular concern and must be weighed carefully against the risk of traumatic brain injury that could cause permanent damage or death if not identified early. If the new guidelines are applied appropriately, the use of CT scans nationwide could be significantly reduced.

The effort was made possible by the Pediatric Emergency Care Applied Research Network, or PECARN, which enabled the massive collection of data. Supported by the U.S. Department of Health and Human Services’ Emergency Medical Services for Children Program, PECARN is the first federally-funded, multi-institutional network for research in pediatric emergency medicine in the nation. The network conducts research into the prevention and management of acute illnesses and injuries in children and youth across the continuum of emergency medicine and health care.

“Children with medical and traumatic illnesses usually have good outcomes, but you need a lot of children to assess factors and treatments that predict both good and bad outcomes. By studying large numbers of children, in a variety of settings and from diverse populations, the results will more likely be applicable to the general population. That’s the power of PECARN,” Kuppermann said. “Combined, our network of emergency departments around the country evaluates approximately 1 million children per year.”

Along with the UC Davis team, key PECARN researchers in the Lancet study included Peter S. Dayan from New York-Presbyterian Hospital and Columbia University Medical Center in New York; John D. Hoyle Jr. from Helen DeVos Children's Hospital in Grand Rapids; Shireen M. Atabaki from Children’s National Medical Center in Washington, D.C.; and Richard Holubkov from the PECARN Data Coordinating Center at the University of Utah.

Charles Casey is a senior public information representative for the UC Davis Health System.