Using validated prediction rules to identify children with very low risk of brain injury from head trauma can reduce the need for CT scans and accompanying radiation exposure, according to a study published today in the Lancet.

Nathan Kupperman, PhD, from the departments of emergency medicine and pediatrics at the University of California, Davis Medical Center in Sacramento, Calif., and colleagues analyzed more than 42,000 children, a quarter of whom were under two years of age, and the rest of whom were between the ages of two and 18.

They enrolled patients younger than 18 years presenting within 24 hours of head trauma with Glasgow Coma Scale scores of 14-15 in 25 North American emergency departments.

"Our aim was to identify children at very low risk of clinically-important traumatic brain injuries (ciTBI) for whom CT might be unnecessary," the authors wrote.

They derived and validated age-specific prediction rules for ciTBI (death from traumatic brain injury, neurosurgery, intubation less than 24 hours or hospital admission of two nights or longer).The prediction rules were created using a derivation population and then applied to see if they worked on a validation population.

CT scans were obtained on 35 percent (14,969) of the children. The authors stated that ciTBI occurred in 1 percent of them, and 0.1 percent underwent neurosurgery.

In the validation population, the prediction rule for children younger than two years (normal mental status, no scalp hematoma except frontal, no loss of consciousness or loss of consciousness for less than five seconds, non-severe injury mechanism, no palpable skull fracture, and acting normally--according to the parents) had a negative predictive value for ciTBI of 100 percent and sensitivity of 100 percent.

Almost a quarter (167 of 694) of CT-imaged patients younger than two years were in this low-risk group.

The authors wrote that the prediction rule correctly identified 100 percent of 1,176 patients younger than the age of two in the validation population who did not have a ciTBI.

The prediction rule for children aged two years and older (normal mental status, no loss of consciousness, no vomiting, non-severe injury mechanism, no signs of basilar skull fracture, and no severe headache) had a negative predictive value of 99.95 percent and sensitivity of 96.8 percent.

A little over one-fifth (446 of 2,223) of CT-imaged patients aged two years and older were in this low-risk group.

"Neither rule missed neurosurgery in validation populations," the authors noted.

On the basis of their data, the authors concluded: "These validated prediction rules identified children at very low risk of ciTBIs for whom CT can routinely be obviated."