New research shows that kids’ seating arrangements in cars could affect their chances of injury in side-impact car crashes.

“Side impacts are the second most common fatal crash type after frontal crashes and require focused attention from the safety community,” says Kristy Arbogast, PhD, in a news release.

The findings include:

—Lower injury risk for kids aged 4 to 8 in belt-positioning booster seats (especially high-backed models).

—Lower injury risk for kids aged 4 to 15 sitting with other children in a vehicle’s rear row (and wearing seatbelts).

The data come from researchers including the associate director of field engineering for TraumaLink, a comprehensive pediatric trauma research center at The Children’s Hospital of Philadelphia and the University of Pennsylvania.

The studies were presented in Boston at the 49th Annual Scientific Conference of the Association for the Advancement of Automotive Medicine.

Booster Seat Study

Belt-positioning booster seats for kids aged 4 to 8 were one of Arbogast’s topics.

Kids in belt-positioning booster seats were 58 percent less likely to be injured in a side-impact crash, compared with kids wearing seatbelts who weren’t in booster seats, the researchers say.

That’s similar to their previous findings, Arbogast and colleagues note.

Children in booster seats were found to be less likely to have head and facial injuries, as well as injuries to the abdomen and spine, which the researchers call “seat belt syndrome.”

Booster Seat Type

High-back booster seats showed a bigger drop (70 percent) in injury risk in children aged 4 to 8. Backless booster seats didn’t show a significant injury reduction advantage over seat belts alone, the researchers note.

Arbogast and colleagues suggest two possible reasons: the seats’ designs and not using the shoulder belt positioner on backless booster seats. The positioner is attached to the seat’s bottom by a strap of webbing, the researchers say.

The differences in results for the two seat types should be viewed with caution, write the researchers. Their study didn’t include large numbers of affected children — especially those in backless booster seats. That leaves room for some uncertainty, which should be addressed in future research, note the researchers.

Sitting in the Rear Row

In another study, Arbogast’s team focused on seating arrangements for children aged 4 to 15 during side-impact crashes in passenger cars.

When the kids had seatmates in a vehicle’s rear row — and all were wearing seatbelts — their injury risk in side impact crashes was 58% lower than when kids had the rear row to themselves, the study shows.

“Occupants are at an increased risk of injury if they sit alone on their row as compared to sitting with other occupants,” write the researchers.

No matter where kids sat in the rear row of passenger cars, head injuries were “by far” the most frequent injuries in side-impact crashes, the researchers write. That was especially true for kids in the center seat or on the side of the car that got hit.

In a third study, Arbogast and colleagues found that kids in passenger cars and light trucks (including SUVs) were more likely to be seriously injured if their vehicle was hit by a light truck instead of a passenger car or minivan.

All of Arbogast’s studies were based on a large database of insurance claims from State Farm Insurance Companies between December 1998 and December 2004.

Seating Your Child Safely

According to the American Academy of Pediatrics (AAP), the following guidelines can be used to choose a safety seat that fits your child’s age and size:

—Use a rear-facing seat until your child is at least 1 year and weighs at least 20 pounds.

—Use a forward-facing seat with harness until your child is too tall or too heavy for the seat. According to the AAP, this is usually at a weight of 40 pounds or when the child’s ears reach the top of the car seat — check the seat instructions to be sure.

—Use a belt-positioning booster seat until an adult seat belt fits properly — the child will be about 4 feet 9 inches tall. The AAP says that for children to fit into an adult seat belt, make sure the shoulder belt lies across the chest, the lap belt lies on the upper thighs, and the child is tall enough to sit against the vehicle seat back with legs bent at the knees and feet hanging down. A lap-and-shoulder seat belt can be used by children once the adult seat belt fits properly.

By Miranda Hitti, reviewed by Brunilda Nazario, MD

SOURCES: 49th Annual Scientific Conference of the Association for the Advancement of Automotive Medicine, Boston, Sept. 11-14, 2005. News release, The Children’s Hospital of Philadelphia. American Academy of Pediatrics.