Uninsured Americans often have difficulty getting care and paying for medications. But what happens once they are admitted to a hospital with a life-threatening illness?

A new study finds that even after they have heart attacks or strokes and are admitted to hospitals, the uninsured are more likely to die than those who carry private insurance. A gap persisted even after the researchers adjusted for disparities in the patients’ underlying health, socioeconomic status and other factors.

Researchers analyzed more than 150,000 hospital discharges of working-age Americans, ages 18 to 64, who were hospitalized for one of three leading causes of inpatient deaths: heart attack, stroke and pneumonia. The data was drawn from the 2005 Nationwide Inpatient Sample.

The study found that uninsured patients who had heart attacks were 52 percent more likely to die in the hospital than the privately insured, and those who had a stroke were 49 percent more likely to die in the hospital.

“We thought there would be some disparity and a little bit of a difference, but we were surprised there were such significant differences,” said Dr. Omar Hasan, a hospitalist at Brigham and Women’s Hospital in Boston who was the lead author of the study, in the Journal of Hospital Medicine.

One reason, Dr. Hasan suggested, may be that patients who have trouble getting care may have more advanced disease. “We know for a fact that people who are uninsured delay seeking care,” he said, adding, “Stroke and heart attack are a result of things that happen to the body and the blood vessels over many years.”