The risk of death among uninsured people ages 50 to 64 is 43% higher than it is for people in that age group who have insurance, according to a study in Health Affairs. That could mean that more than 105,000 U.S. residents in that age group will die prematurely in the next eight years because they lack insurance.

The researchers said that if lack of health insurance were categorized as a disease, it would be the third-leading cause of death among the near-elderly, behind heart disease and cancer. They predicted that if policymakers do not work to expand health coverage, the number of unnecessary deaths among adults in that age group could grow to more than 30,000 per year by 2015 as baby boomers age.

"The consequences of being uninsured are growing more severe, especially for this older age group," said lead author Dr. J. Michael McWilliams of Brigham and Women's. "We were surprised by the sheer number of preventable deaths."

Deborah Banda, director of AARP for Massachusetts, called the findings "appalling" and said the report "adds another level of urgency to finding a solution to the problem" of the uninsured.

For the study, researchers from Brigham and Women's Hospital used data from the National Institute on Aging on 8,736 adults in 1992, dividing them into two groups -- those who were publicly or privately insured and those who weren't.

By examining the number of deaths by the year 2000, the researchers found that lack of insurance increased risk of death by 43%, even after adjusting for the fact that the uninsured are frequently sicker or have lower incomes.

In addition, the researchers found that low-income uninsured participants were 53% more likely to die early, and those with diabetes, heart disease or high blood pressure were also found to be more vulnerable.

According to the study, the difference in mortality rates between insured and uninsured adults was found only in whites, not in non-Hispanic, black or Hispanic adults.

An abstract of the data is available on the Health Affairs Web site.