Mower County Sheriff Terese Amazi wasn't at all surprised to hear that men accounted for less than half of all reported traffic injuries in Minnesota last year.
"Men are just by their very nature more reluctant to report an injury," Amazi said, recalling an incident in her county in which a young male driver appeared uninjured and told troopers he was fine. Officers checked the "not injured" box at the scene, but it turned out later that he had a ruptured aorta.
"He could have bled to death," Amazi said.
The example is extreme, but several Minnesota experts who study crash data agreed that reporting discrepancies could be a possible explanation for an apparent gender gap in motor vehicle crash injuries in the state. Men account for two-thirds of all traffic fatalities, but women are injured at a higher rate, leaving some experts scratching their heads.
The gap is even more pronounced at hospital emergency departments, where most patients who come in with minor to moderate crash injuries are treated and released. In 2009, the latest data available, the rate of motor vehicle injury at hospital emergency departments was 266 per 100,000 for men but 371 per 100,000 for women.
"It's impressive," said Mark Kinde, who leads the injury and violence prevention unit for the Minnesota Department of Health (MDH). "These are real hospital reports. Women are going to the hospital more than men."
According to Centers for Disease Control data, the trend occurs nationally, too. In 2009, women were being injured in crashes at a rate of 969 per 100,000 compared to 763 per 100,000 for males.
The difference between the female vs. male rates for the less severe injuries is striking. I don't have a ready explanation for thatMark Kinde, Minnesota Department of Health
When looking at the most severe injuries, men account for a higher percentage. For example, women accounted for just 42 percent of patients admitted to Hennepin County Medical Center for crash injuries in the last five years.
Julie Philbrook, an HCMC nurse who specializes in trauma prevention, said it makes sense that males would account for more of the severe injuries because studies have shown males tend to do more risky driving. Males have lower seat-belt use rates and account for more than two-thirds of drunken driving incidents in Minnesota.
The fact that more women are being treated for less severe crash injuries might have something to do with the kind of driving they're doing, Philbrook said.
"One of the thoughts is that women are driving more and possibly commuting further," she said. "If you look at the patterns, are women doing more of the residential driving — driving to school, driving to the store?" MDH's Kinde said he would look at car design and also compare men and women in terms of how often they drive or ride in a car.
"The difference between the female vs. male rates for the less severe injuries is striking. I don't have a ready explanation for that, but it's certainly worth probing," he said.
In 2010, traffic crashes in the state cost nearly $1.5 billion, according to the Minnesota Department of Public Safety's annual report. Minor and moderate injuries accounted for 30 percent of that total.
The Department of Public Safety reports some gender differences as part of its annual "Crash Facts" report, but not in a comprehensive way that would help explain the gap. For instance, the department reported that men made up at least 54 percent of all drivers involved in crashes last year, but we don't know what percentage of passengers involved in crashes were men or women.
In fatal crashes not involving motorcycles, bicycles or pedestrians, 71 percent of those killed were driving. A comparable percentage for injuries wasn't part of the report.
Nathan Bowie, a Department of Public Safety spokesman, said no scientific study had been done on Minnesota crash data to explain the gender gap. Bowie said state public safety experts cite a few possibilities: the physical differences between men and women and the fact that more women than men buckle up, meaning they might be surviving crashes at higher rates.
The physical differences between men and women could definitely play a role in a crash, said St. Paul chiropractor Everett Wells.
"Their ligaments tend to be looser. They translate a lot more when you're getting in that collision, and women get hurt a lot more because of that," he said.
Studies have also shown that men have more of a certain pain-suppressing hormone than women, Wells said. And in live crash tests, researchers found that seat belt related injuries tend to affect the shoulder for men and the neck for women because of where the shoulder harness is.
Another factor is a person's weight. Most men weigh enough to cause their seat back to break backwards, but that isn't the case with many women, Wells said.
"A woman doesn't have enough mass to make that seat ride down the way it's supposed to, so she absorbs more of the energy coming from that crash," he said.
But Wells and Rick Zarmbinski, another Twin Cities chiropractor, agreed that the discrepancy in the numbers might also be related to a difference in who's seeking care for an injury.
"In general, women get care more often than men. That's really across every medical profession," said Zarmbinski, who has been practicing for more than 30 years.
A recent University of Minnesota survey of chiropractors found that more than 60 percent of people seeking care were women, he said.
There are more possible explanations for the apparent gender gap. William Mech, an actuary who works for the insurance industry, said the list could also include the different impacts of a crash on drivers versus passengers. In some crashes, drivers can see the crash coming and might be able to shield themselves from the impact while their passengers are caught off guard.
Time of day, whether it happened in an urban or rural area and whether there were distractions could also be factors — all variables the insurance industry might use when determining rates for a given person, Mech said.
With such a long list of factors, he cautioned against jumping to conclusions.
"It's not necessarily a gender gap. It might be a lifestyle gap," Mech said. "You have to control for all those other things before you can say this is what's happening."