Estimated 300 Children Died In The U.S. From Shaken Baby Syndrome Last Year

"We did this research because inflicted head trauma, also called shaken baby syndrome, is one of the leading causes of death due to child abuse," said lead investigator Dr. Heather T. Keenan, research assistant professor of social medicine at the UNC School of Medicine. "Since there were no population-based estimates of how many children were being hurt, we conducted a population-based study to try and find out what the incidence of inflicted traumatic brain injury was.

"Also, we wanted to know which children were getting hurt," Keenan said. "We found that approximately 30 per 100,000 children under age 1 suffered inflicted brain injuries."

Having younger mothers and being under age 1 were risk factors, but the injuries occur in all racial and socioeconomic groups, she said.

"To our knowledge, ours is the first study of its kind to quantify shaken baby syndrome in the nation's youngest children."

A report on the findings appears in the Aug. 6 issue of the Journal of the American Medical Association.

Keenan and colleagues identified all N.C. children ages 2 years and younger admitted to a pediatric intensive care unit in the state or who died from a brain injury in 2000 and 2001. Members of the team contacted charge nurses at each of the state's nine pediatric ICUs three times a week over the span, checked medical examiner and other records and even queried the three closest out-of-state pediatric ICUs about N.C. patients. They considered the injuries to be inflicted if suspects confessed or if a medical or social service agency determined abuse.

"We found 152 cases of serious or fatal traumatic brain injuries over the two years," the physician said. ""Out of 230,000 children under age 2 in North Carolina, 80 were injured from shaken baby syndrome."

Although they confined their study to one state, the researchers believe the incidence figures to be generally representative of what happens across the nation, Keenan said. This would translate to an estimated 306 children dying in a year from shaken baby syndrome. An earlier, comparable study conducted in Scotland showed a similar incidence there, but the UNC study was more precise because of its larger base population.

Further analysis and calculations showed infants were at almost eight times the risk of children between ages 1 and 2, she said. Boys faced close to twice the risk of girls.

Having extended family in the home and having a parent in the military boosted the risk of inflicted injuries. Children whose fathers lived at home and whose mothers had more than a high school education faced a lower risk.

The research likely underestimates the problem, Keenan said.

"We studied only children who had serious enough injuries to present to an intensive care unit," she said. "Many children may never present for medical care after the first episode of inflicted traumatic brain injury, and of those who do present for medical care, many may be missed because of the non-specificity of complaints in infants with head injuries."

Co-authors of the JAMA article were Dr. Desmond K. Runyan, professor and chair of social medicine and professor of pediatrics; Dr. Stephen W. Marshall, associate professor of epidemiology in the School of Public Health and of orthopedics in the medical school; and Mary Alice Nocera, social research associate and project manager. Drs. David F. Merten, former clinical professor of radiology at UNC, and Sara H. Sinal, professor of pediatrics at the Wake Forest University, contributed to the study.

Keenan, Runyan, Marshall and Nocera are affiliated with the university's Injury Prevention Research Center.

"We hope this study will be helpful in making physicians more sensitive to the diagnosis," Keenan said. "It is important to have this baseline information so that when preventive interventions are done, we have a way to judge our possible success."

Earlier research suggested that inflicted traumatic brain injuries might affect children's development more than non-abusive brain injuries do, she said. Estimates of deaths from the former range from 15 percent of cases to 38 percent, and permanent nerologic damage among survivors is common and can be severe.

The Centers for Disease Control and Prevention sponsored the research.