(Agencies)
Updated: 2008-03-14 10:46

US citizens who have more than 12 years of education can expect to live seven years longer, a new study reveals.

Those with more than 12 years of education -- more than a high school diploma -- can expect to live to 82; for those with 12 or fewer years of education, life expectancy is 75.

"If you look in recent decades, you will find that life expectancy has been increasing, which is good, but when you split this out by better-educated groups, the life expectancy gained is really occurring much more so in the better-educated groups," said lead researcher Ellen R. Meara, an assistant professor of health care policy at Harvard Medical School.

"The puzzle is why we have been successful in extending life span for some groups. Why haven't we been successful in getting that for less advantaged groups?" Meara asked.

The answer may lie with tobacco, the study found. About one-fifth of the difference in mortality between well-educated and less-educated groups can be accounted for by smoking-related diseases such as lung cancer and emphysema, Meara said.

But the disparity in life expectancy is not only a function of education, Meara said. "Those with less education are likely to have lower income. They're likely to live in areas that have their own health threats, either through crime or poor housing conditions. In addition, they may have worse access to health insurance coverage and health services," she said.

For the study, Meara's team collected data on people who took part in the National Longitudinal Mortality Study. The researchers used death certificates, plus estimates from Census data, to create two datasets -- one covering 1981 to 1988 and the other from 1990 to 2000.

The researchers found that in both datasets, life expectancy rose but only for people with more than 12 years of education. For those with 12 years of education or less, life expectancy remained flat through the periods.