Dr. Sripal Bangalore of New York University's Langone Medical Center and Dr. Franz H. Messerli of St. Luke's Roosevelt Hospital at Columbia University College of Physicians and Surgeons in New York, examined data for 27 developed countries.
The gun ownership data were obtained from the Small Arms Survey, and the data for firearm-related deaths were obtained from a European detailed mortality database from the World Health Organization, the National Center for Health Statistics and others.
"The gun ownership rate was a strong and independent predictor of firearm-related death," Bangalore said in a statement. "Private gun ownership was highest in the United States. Japan, on the other end, had an extremely low gun ownership rate. Similarly, South Africa at 9.4 firearms-related deaths per 100,000 and the United States at 10.2 per 100,000 had extremely high firearm-related deaths, whereas the United Kingdom, at 0.25 per 100,000, had an extremely low rate of firearm-related deaths."
There was a significant correlation between guns per head in each country and the rate of firearm-related deaths, with Japan being on one end of the spectrum and the United States on the other, the study found.
"This argues against the notion of more guns translating into less crime," Bangalore said.
The researchers used age-standardized, disability-adjusted, life-year rates due to major depressive disorder per 100,000 inhabitants with data obtained from the World Health Organization database as a presumed indicator for mental illness burden in each country to assess whether there was a correlation between mental illness burden of a country and the crime rate in a country. The study found no significant correlation between mental illness and crime rate.
"Although correlation is not the same as causation, it seems conceivable that abundant gun availability facilitates firearm-related deaths. Conversely, high crime rates may instigate widespread anxiety and fear, thereby motivating people to arm themselves and give rise to increased gun ownership, which, in turn, increases availability," the researchers said. "The resulting vicious cycle could, bit by bit, lead to the polarized status that is now the case with the United States."
Regardless of exact cause and effect, the current study debunks the widely quoted hypothesis that countries with higher gun ownership are safer than those with low gun ownership, Bangalore and Messerli said.
The findings were published in The American Journal of Medicine.