New York ? Americans worry that inflation and the rising cost of health care are increasing the risk that they will run out of money in retirement, according to a study released Monday.

The survey by the Society of Actuaries found that people already retired were most worried about inflation and affording long-term care. Pre-retirees, meanwhile, ranked affordable health care as their top concern, followed by inflation and long-term care coverage.

Overall, pre-retirees showed greater worries than those already in retirement, the study found.

Anna M. Rappaport, a consulting actuary based in Chicago and supervisor of the biennial report, said that one theory for the difference in the levels of concern could be that “for the pre-retiree, retirement is still an unknown.”

Rappaport also said that Americans appear to be underestimating the financial impact of the death of a spouse. About 60 percent of those responding to the survey felt there would be little impact when a spouse dies, but Rappaport said surviving spouses often experience significant drops in income and benefit coverage, especially women.

She said Americans need to be more aware that longevity is a significant risk. She pointed out that among today’s 65-year-old population, the average man is likely to live an additional 17 years and the average woman, 20 years.

The study found both a lack of understanding about investing – which can help people grow their savings above the rate of inflation – as well as inadequate savings levels. It also found that people “do not estimate their retirement needs well.”

Still, Rappaport said, many Americans are considering a step that could help: working longer.

The survey involving more than 800 adults age 45 to 80 was conducted in mid-2007 by Mathew Greenwald & Associates Inc. and had a margin of error of plus or minus 5 percentage points.