Life expectancy, among other statistics including maternal mortality, is one measure by which a country’s success in the health realm is determined. A higher life expectancy is associated with higher quality of life and better healthcare. The United States is considered a developed, high-income country, but American citizens experience lower life expectancy at birth than many other high-income countries, according to new research.

Most research on life expectancy centers on the 50 and older population and their mortality. However, much of the expectancy gap between the U.S. and other countries is due to mortality at younger ages, which leads to many decades of potential life being lost. This early mortality is dominated by injury deaths, so Dr. Andrew Fenelon of the National Center for Health Statistics and colleagues decided to estimate the contribution of three large causes of injury death to the gap in life expectancy between the U.S. and 12 comparable countries.

The researchers looked at the top three largest causes of U.S. injury death — motor vehicle traffic crashes, firearm-related injuries, and drug poisonings. These causes are collectively responsible for more than 100,000 deaths every year. The team gathered the statistics from the U.S. National Vital Statistics System and the World Health Organization Mortality Database, and calculated the death rates by age, sex, and cause for 12 high-income countries alongside the U.S.: Austria, Denmark, Finland, Germany, Italy, Japan, the Netherlands, Norway, Portugal, Spain, Sweden, and the United Kingdom.

Fenelon and his colleagues found that men in the comparison countries had a 2.2-year life expectancy advantage over U.S. men (78.6 years vs 76.4 years). Women experienced the exact same advantage, at 83.4 years in comparison countries vs 81.2 years in the U.S. The injury causes of death were responsible for 48 percent of the life expectancy gap among men — firearm related injuries accounting for 21 percent, drug ppisonings at 14 percent, and motor vehicle crashes at 13 percent. For women, these three causes accounted for 19 percent of the gap, with 4 percent from firearms, 9 percent from drug poisonings, and 6 percent from crashes.

Overall, the top three injury causes were responsible for 6 percent of deaths among U.S. men and 3 percent among U.S. women. The U.S. death rates from injurious causes exceeded those in every comparison country.

“Although the reasons for the gap in life expectancy at birth between the United States and comparable countries are complex, a substantial portion of this gap reflects just 3 causes of injury,” the authors wrote.

The research appears in the Feb 9 issue of JAMA.

Source: Fenelon A, Chen L, Baker S. Major causes of injury death and the life expectancy gap between the United States and other high-income countries. JAMA. 2016.