For the more than 4 million uninsured adults in the U.S. nearing retirement age, a serious illness often spells financial disaster, a recent study has found.

"We found that for a typical household this costs—in lost savings—between one-third and one-half of their total accumulated financial assets relative to households with similar, but insured individuals," says lead author Keziah Cook, a Ph.D. candidate in economics at Northwestern University, in Evanston, Ill.

Uninsured adults who developed a major medical problem before retirement typically lost $4,176 more than similar insured adults did.

Near-elderly adults with insurance who experienced a major illness generally didn't suffer a decline in wealth, the analysis shows.

The study appears online in the journal Health Services Research.

Cook and colleagues analyzed 14 years of data from the Health and Retirement Survey, an ongoing survey of 22,000 Americans over 50. They focused on households with an adult between ages 51 and 64 who recently had received a diagnosis of a major medical problem, such as cancer, diabetes, heart or lung disease, stroke, or emotional or psychiatric disorders.

The analysis examined changes in nonhousing wealth only, such as checking and savings accounts, certificates of deposit, and stocks and bonds, and did not include housing equity.

"Newly ill people without insurance do suffer large asset loss," says Dr. Bruce Kinosian, an associate professor of general medicine and a geriatrician at the Hospital of the University of Pennsylvania, in Philadelphia.

However, Kinosian says that the authors' findings on asset changes in the insured might be less reliable, in part because they didn't consider nonmedical direct expenses that might occur after a new illness, such as lost wages or job loss.

The findings suggest that the existing private health insurance system in the U.S. is sufficient to protect the financial assets of people nearing retirement age, but that expanding the current health care system could help protect the assets of all Americans, the authors say. However, it isn't clear whether expanding access is "achievable or affordable," they say.

"Until such reforms are implemented, millions of Americans are potentially one illness away from financial catastrophe," Cook and colleagues conclude.