Among emergency department visits in 2005 that resulted in hospitalization, pneumonia topped the list of reasons for the visit. Two-thirds of the 669,500 of those who came to emergency rooms with pneumonia were admitted, a report issued by Agency for Healthcare Research and Quality said.

The chances of being admitted were smaller for uninsured patients, about 7 percent, than patients with private insurance or Medicaid, about 14 percent each, or Medicare, nearly 40 percent. Patients who were uninsured accounted for about 18 percent of hospital emergency department visits, the AHRQ report said.

The top three reasons for visiting a hospital emergency department were: 2.4 million visits for sprains and strains; 2 millions visits for bruises and other superficial injuries; and 1.7 visits for abdominal pain. In each of those categories, however, less than 5 percent of patients were admitted to the hospital, the report said.