(Reuters Health) - Shareable, two-wheeled standing scooters, which are the rage in some West Coast cities, may be more risky to riders - and pedestrians - than people think, researchers say.

The battery-powered devices look like a skateboard with handlebars. Reviewing injury data from two Los Angeles-area emergency rooms over the course of a year, researchers found that patients whose injuries involved these scooters outnumbered patients with bicycle-related emergencies.

Among 249 patients admitted with standing-scooter-related injuries, 100 had head injuries, 79 had broken bones and 69 had contusions, sprains and lacerations without a fracture or head injury. Most patients were discharged to home from the emergency room, but 15 were hospitalized and two required admission to the intensive care unit. Just 10 patients had been wearing a helmet when their accident occurred.

On the plus side, the scooters are “a really innovative and inexpensive means of transportation,” said senior study author Dr. Joann Elmore, a professor of medicine at the David Geffen School of Medicine at the University of California, Los Angeles. “But riders seem to underestimate the hazards. I encourage everyone who uses them to be careful to follow the traffic laws and to wear helmets.”

Wearing a helmet would be a safe approach since the scooters can zip around at 15 miles per hour, but it’s not mandatory since California just passed a law that says helmets are not required, Elmore noted.

Standing electric scooters that are available for rent through a smartphone app were first introduced in Santa Monica in September 2017, the study team writes in JAMA Network Open. Now the scooters are available in 60 U.S. cities and 6 international cities and local officials have devised varying regulations around the devices. Some require riders to wear a helmet and most ban riding on sidewalks, the authors note.

The researchers looked at patterns of scooter-related injury and users’ behavior between September 1, 2017 and August 31, 2018 using emergency room records from two major local hospitals.

While most injuries occurred when people fell off their scooters, some happened when scooters tangled with pedestrians. Of the 249 patients, 21 were pedestrians. Eleven pedestrian injuries were the result of someone being hit by a scooter, while five occurred when a pedestrian tripped over a “parked” scooter and five were the result of a pedestrian trying to lift or carry a scooter that was not in use.

Most riders were adults, but 27 were under age 18.

“Our findings are probably conservative since we only included cases that we were certain were due to electric scooters and we were looking early on when there weren’t as many of them around,” Elmore said. “Also, these were only the patients seen in the emergency department, not those seen in outpatient clinics.”

“It’s a very timely contribution to an emerging injury risk,” said Dr. Guohua Li, director of the Center for Injury, Epidemiology and Prevention at Columbia University’s Mailman School of Public Health in New York City, who wasn’t involved in the study. “I was in San Diego two months ago at a conference and (the scooters) were everywhere. They are not just a risk to the riders, but also the pedestrians.”

The new study is “raising awareness that there is this new vehicle out there and its use is growing rapidly,” said Dr. Barbara Gaines, director of Trauma and Injury Prevention at the Children’s Hospital of Pittsburgh at the University of Pittsburgh Medical Center.

Gaines hopes the study will alert municipalities and spark new regulations about how and where the scooters can be used. Chief among her concerns is the large number of head injuries and she’s hoping local governments will pass laws requiring helmet use.

“As with any new product, it’s important to objectively look at the data to see where the risk lies,” said Dr. Leticia Ryan, director of research in the pediatric emergency medicine division at the Johns Hopkins University School of Medicine in Baltimore. “That can help us develop safer ways to use these scooters.”

SOURCE: bit.ly/2UecB39 and bit.ly/2MviqGV JAMA Network Open, online January 25, 2019.