"Cars, guns and drugs are the unholy trinity causing the majority of injury deaths in the U.S.," said lead study author Sage Myers, from the Perelman School of Medicine at the University of Pennsylvania in Philadelphia.
Researchers from UPenn and the Children's Hospital of Philadelphia (CHOP), analyzed all 1,295,919 injury deaths that occurred in the U.S. between 1999 and 2006, though deaths related to 9/11 were excluded due to the "unusual nature" of the tragedy.
Motor vehicle crashes were the leading cause of injury death, resulting in 27.61 deaths per 100,000 people in most rural areas and 10.58 per 100,000 in most urban areas.
"Although the risk of homicide is higher in big cities, the risk of unintentional injury death is 40 percent higher in the most rural areas than in the most urban," Myers said. "And overall, the rate of unintentional injury dwarfs the risk of homicide, with the rate of unintentional injury more than 15 times that of homicide among the entire population."
Risk of firearm-related death for the population as a whole showed no difference across the rural-urban spectrum, however, when factoring age, firearm-related deaths were significantly higher in rural areas for children and people 45 years and older. For people aged 20 to 44, the risk was significantly lower in rural areas.
The data, published in the Annals of Emergency Medicine, also showed surprising results when factoring education, income and race.
Rural counties with the highest education and median income levels had significantly increased risk of injury death compared to rural counties with the lowest levels of each.
Rural counties with large black populations had significantly lower risk of injury death than those with small black populations.
For rural Latinos, the opposite was true. Rural counties with large Latino populations had significantly higher risk of injury death than rural counties with small Latino populations.
"By digging deep into the data, we may be able to tailor injury prevention efforts to the populations that need them, such as seniors in cities who are more likely to fall and rural children who are more likely to drown," said Dr. Myers.
Researchers suggest creating injury priority scores based on statistically likely injuries in a given area, and tailoring emergency and trauma departments to equip, staff and respond accordingly.