TUESDAY, April 17 (HealthDay News) -- Adults with serious injuries are more likely to survive if they're transported to hospital by helicopter instead of ambulance, researchers report.

For the study, Dr. Adil Haider, of Johns Hopkins University School of Medicine in Baltimore, and colleagues examined data on more than 220,000 patients aged 15 and older with serious injuries who were admitted to level-one (top-ranked) or level-two trauma centers in the United States.

The overall death rate for the nearly 62,000 patients transported by helicopter was 12.6 percent, compared to 11 percent for the nearly 162,000 patients transported by ground. The researchers also noted that a greater percentage of patients transported by helicopter had more severe injuries.

Further analysis showed that for patients taken to level-one trauma centers, helicopter transport was associated with a 16 percent improved chance of survival compared to ground transport. For patients taken to level-two trauma centers, helicopter transport was associated with a 15 percent better chance of survival compared to ground transport.

"Thus, for patients transported to level-one trauma centers by helicopter, 65 patients would need to be transported to save one life; for patients transported to level-two trauma centers, the number needed to treat is 69," Haider and colleagues reported.

"Trauma remains the leading cause of death and disability among young people around the world. In the United States, more than 50 million people are injured per year, resulting in approximately 169,000 annual deaths and a lifetime cost of $406 billion," the authors wrote in the report, which is published in the April 18 issue of the Journal of the American Medical Association, a special theme issue focusing on comparative effectiveness research.

It's not clear why helicopter transport improves patients' chances of survival, Haider's team noted in a journal news release, and because the use of helicopters to transport seriously injured patients is expensive, further research into the issue is recommended.

One expert agreed that more research is needed.

Dr. Daniel Baker, associate medical director in the department of emergency services at Lenox Hill Hospital in New York City, noted that the study did not control for two key variables -- time of transportation and the level of medical training for helicopter vs. ground crews. So, the findings "do not indicate whether it is actually the transportation by the helicopter itself that lends the increased benefit to the patient," he said.

Furthermore, "multiple areas throughout the country do not have access to transport by helicopter," Baker noted. "Hopefully in the future, further prospective studies can be performed to help determine what the underlying benefit is so that it may be applied to all trauma victims."

More information

The U.S. Centers for Disease Control and Prevention has more about injury and violence prevention and control.