By Mary Gillis

(Reuters Health) – Wearing a seatbelt may not prevent liver injuries in a car crash, but it could lessen their severity and make a major difference in the accident’s consequences and costs, researchers say.

Among more than 50,000 people with liver injuries as a result of a car crash, those with severe liver injuries were twice as likely to die as those with mild or moderate liver injuries, researchers found.

They also found that people who were wearing seatbelts were much less likely to have a severe liver injury. The risk dropped a bit more when seatbelts and airbags were both used, but airbags alone did not affect injury severity.

“It has been known for some time that seatbelt use is associated with lower mortality in a car crash,” said lead author Audrey Renson of NYU Langone Hospital-Brooklyn in New York City.

“Although some may consider this common sense, there is still some controversy lingering around seatbelts possibly being harmful and that having an airbag means you don’t have to wear a seatbelt,” she said in an email.

Each year in the U.S., motor vehicle crashes result in 2 million emergency room visits, tens of thousands of deaths and a huge financial burden to the healthcare system of nearly $1 trillion dollars, the study team writes in the Journal of Epidemiology and Community Health.

Blunt abdominal trauma specifically accounts for a significant number of injuries in these accidents, they add.

The two most commonly injured organs after such a collision are the liver and spleen, said Dr. Eileen Metzger Bulger, chair of the American College of Surgeons Committee on Trauma and chief of trauma at Harborview Medical Center in Seattle, who was not involved in the study.

“Both can cause severe bleeding, but the spleen can be removed if needed during surgery, which controls the bleeding. The liver (however) is critical for life and cannot be removed,” Bulger said by email.

Renson’s team analyzed data from the National Trauma Data Bank for 2010 through 2015 on patients 18 years and older who were in a vehicle crash, excluding motorcycles, and were either admitted to the hospital or died on arrival or en route.

The researchers classified liver injuries as low-grade or severe. Low-grade injuries included blood clots or shallow lacerations and others that rarely require surgery. Severe injuries included ruptured clots with uncontrolled bleeding, deep lacerations and other kinds of wounds that need immediate repair.

Overall, 51,202 injury cases included enough data to calculate an injury severity score, the researchers note. Fifteen percent of patients had liver injuries in the severe category, and 15 percent of those patients died. Among patients with mild or moderate liver injuries, nearly 8 percent died.

About 14 percent of patients with severe injuries required surgery and 21 percent had some kind of complication, versus 5 percent and 15 percent, respectively, of those with less severe liver injuries.

Seatbelt-wearing patients were 21 percent less likely to suffer a severe liver injury, and those protected by both a seatbelt and airbag were 26 percent less likely.

Seatbelts and airbags appear to work together, Renson said, and the effect of one is dependent on the other.

“Trauma can result in a number of serious complications during the period surrounding the trauma, including bile leakage or obstruction of bile flow, abscess formation, bleeding without the ability to appropriately clot blood and an inability to filter metabolites resulting in jaundice,” noted the study’s senior author, Dr. Marc Bjurlin, a surgeon at NYU Langone Hospital-Brooklyn.

While the results of the study might seem obvious, the findings reinforce the importance of wearing a seatbelt at all times, he said.

SOURCE: Journal of Epidemiology and Community Health, online March 29, 2018.