Findings from a new study blame poor healthcare as the reason why Americans die sooner than citizens from other developed nations.

Researchers from Columbia University in New York found that although life expectancy has improved in the USA over the last thirty years, the numbers in other developed nations are still higher.

The study found that by 2005, 45-year-old women had the lowest survival rate than any of the twelve other nations in the study.

The 15-year life expectancy rate for 45-year-old men also plummeted with a fall from third place in 1975 to twelfth in 2005.

"But what really surprised us was that all of the usual suspects -- smoking, obesity, traffic accidents, and homicides -- are not the culprits," said study author Peter Meunnig in a statement.

"The U.S. doesn't stand out as doing any worse in these areas than any of the other countries we studied, leading us to believe that failings in the U.S. health care system, such as costly specialized and fragmented care, are likely playing a large role in this relatively poor performance on improvements in life expectancy,” he added.

Researchers compared the survival rates over a 15-year period for 45 to 65 year-old males and females in 12 countries, including the USA, UK, Switzerland, Sweden, the Netherlands, Japan, Italy, Germany, France, Canada, Belgium, Austria and Australia.

The study sponsored by the Commonwealth Fund was published in the journal Health Affairs.Fifteen percent of Americans are without health insurance where as the other countries in the study all provide their citizens with universal health insurance.