A new study on emergency rooms disputes the common wisdom that the poor and uninsured are filling them up.

In fact, more than 80 percent of patients seen in emergency rooms have health insurance and a usual source of health care such as a primary care physician, doctors reported on Tuesday.

“Contrary to popular perception, individuals who do not have a usual source of care are actually less likely to have visited an emergency department than those who have such care,” said Dr. Ellen Weber, an professor in the division of emergency medicine at the University of California San Francisco, who led the study.

For the study, Weber and colleagues looked at interviews of nearly 50,000 adults visiting emergency departments in 2000 and 2001.

People without health insurance were no more likely to have had an emergency visit than those with private health insurance, the researchers told a meeting of the American College of Emergency Physicians.

People without a regular doctor or clinic were 25 percent less likely to have had an emergency visit than those with a private doctor, the researchers found.

Their study, also published in the Annals of Emergency medicine, found that 83 percent of emergency department visits were made by people who had a doctor, clinic or were members of a health maintenance organization.

Eighty-five percent had medical insurance and 79 percent had incomes above the poverty level.

“The mistaken belief that emergency departments are overcrowded by a small, disenfranchised portion of the U.S. population can lead to misguided policy decisions and a perception by hospital administrators that emergency patients are not as valuable to the institution as patients having elective surgery,” Weber said in a statement.

“But our findings indicate that emergency departments serve as a safety net, not just for the poor and uninsured, but for mainstream Americans, and in particular those with serious and chronic illness.”

MAJORITY HAVE INSURANCE

A spokesman for the American Hospital Association said he was studying the report but added, “That is not surprising because a majority of people have insurance.”

An estimated 45 million Americans lack health insurance, but that leaves 85 percent of the population with coverage, either public or private.

Hospitals have long complained that their emergency rooms are overcrowded. Between 1992 and 2002, emergency department use climbed 23 percent, from 89.8 million visits to 110 million visits.

The 1986 Emergency Medical Treatment and Labor Act requires any hospital taking part in Medicare - the state-federal health care insurance program for the elderly and disabled - to provide “appropriate medical screening” to anyone showing up at an emergency room and asking for it.

Hospitals say the rules have burdened their emergency departments with poor and uninsured patients seeking care for everyday conditions. Many have closed emergency facilities in recent years.

“Many insurance programs, and particularly public and private HMOs, require beneficiaries to have a primary care physician, which may be expected to improve overall health and health care,” Weber said.

“But the continued rise in emergency visits implies that such programs have not had a substantial impact on overall emergency department use.”

Dr. Steffie Woolhandler of Harvard Medical School and Physicians for a National Health Program agreed. “Many emergency room users have chronic health problems such as congestive heart failure,” said Woolhandler, who advocates for universal national health insurance.