Patients who lack health insurance apparently are more likely to die in the hospital than patients covered by private insurance, researchers reported.

A study involving 529,598 patients found those who did not have insurance were 20 percent to three times as likely to die while they were in the hospital than patients with insurance.Although more research is needed, the findings suggest that a lack of health insurance has a direct impact on the care patients receive, the researchers said Tuesday.

"It does appear that insurance makes a difference," said Jack Hadley, co-director of the Center for Health Policy Studies at Georgetown University School of Medicine.

"It implies that insurance coverage is potentially important to good health," said Hadley, who reported his findings in the Journal of the American Medical Association.

The implications are especially important as lawmakers debate the need for a national health insurance program, Hadley said. Some 35 million Americans do not have health insurance.

"One of the underlying issues is whether having insurance makes any difference in terms of the care people receive or their health outcomes. People who say you don't need national health insurance say there is a safety net and if you need health care you can always get it," he said. "What this study suggests is that may not always be true."

The researchers found those who did not have any type of health insurance tended to enter the hospital with more serious conditions, leave the hospital sooner and were less likely to undergo expensive or discretionary procedures.

But even after accounting for the difference in the conditions of the patients when they entered the hospital, the researchers still found those without insurance had a higher death rate.