FRIDAY, March 4 (HealthDay News) -- Upwards of one-fifth of patients who seek care at one of California's hospital emergency departments leave before being seen by anyone, new research reveals.

Rates of "leaves without being seen" varied widely across the state and according to the type of facility in question. And while the study authors said their results can't be extrapolated to the rest of the nation, the trend does seems to be hitting disadvantaged patients the hardest.

"This is concerning to us as both providers and consumers because these are patients who decided they need care, and we're not able to provide service to them," said study author Dr. Renee Y. Hsia, an assistant professor in the department of emergency medicine at the University of California, San Francisco, as well as an attending physician in the emergency department of San Francisco General Hospital.

Her team found the highest degree of unattended, would-be ER patients at teaching hospitals, county-owned hospitals and trauma centers, all of which experienced about double the rate of unseen patients as other facilities.

The problem appears to be worst among the poorest patients and those most likely to lack insurance coverage. "This either means that over-crowding is the problem, or that these patients have a tendency to walk out more than others," Hsia added. "For now this is just a snapshot, and we don't know the underlying factors at work here yet."

Hsia and her colleagues report their findings in the Feb. 22 online issue of the Annals of Emergency Medicine.

According to the U.S. Centers for Disease Control and Prevention, in 2007 (the same year focused on by the study authors) there were nearly 117 million visits to the nation's ERs. Of those, 18 percent of the patients were seen in less than 15 minutes, and more than 12 percent of all visitors ended up being admitted to the hospital.

California accounts for 12 percent of the nation's population and 7 percent of its hospital market, Hsia's team noted. And over the past 15 years, there's been a steady rise in the number of patients who leave an ER without being seen. That trend has been blamed on a variety of factors, including a drop in general access to care and crowding caused by ER closures, often in lower-income communities.

To explore the specific state of affairs in California, the authors analyzed information obtained from the California Office of Statewide Health Planning and Development database. The data covered all 9.2 million emergency department visits that took place at all 262 non-federally run hospitals across the state during 2007.

Patient income, as well as the affluence of the surrounding community, seemed to play a major role in the findings. ERs in poorer communities had higher rates of patient departures than those located in higher income communities, the study found. Specifically, for every increase of $10,000 in average household income, there was an associated drop in the number of patients who went unseen by ER staff.

Communities with worse insurance coverage also experienced higher rates of unseen patients.

The percentage of people who left emergency departments without being attended to ranged from 0 percent to more than 20 percent, depending on the facility, the report found.

While non-profit hospitals had an average unseen patient rate of 2.5 percent, that figure was twice as high at county-owned hospitals. Similarly, teaching hospitals had more than double the rate of non-teaching hospitals (5.1 percent vs. 2.5 percent), while trauma centers had a 3.9 percent rate compared with 2.5 percent at non-trauma centers.

While Hsia emphasized that more work needs to be done to better understand what's driving people to skip the care they initially felt they needed, she characterized the situation as "serious."

"What's important to combat here is the myth that the people who leave an ER aren't that sick to begin with," she stressed. "That's certainly not true. Most people go to the ER only because they have to. Nobody really wants to go. So it's a sad thing when they make that decision to go, and they need care, and they can't get it."

Dr. Marshall Morgan, chief of emergency medicine at the Ronald Reagan UCLA Medical Center in Los Angeles, concurred.

"I think it's a big mistake for people to assume that the people who are leaving the ERs are people who don't have serious problems," he said. "In fact, it's been shown in other research that among the people who are leaving a certain percentage were seriously ill, as witnessed by their having to come back and be admitted within a few days."

"So we're not just talking about the people with sniffles and sore throats and sprained ankles," Morgan noted. "And this is a very big number. And whether it's because of a general increase in overall volume at ERs across the state due to the general economic issues the country faces today, or for some other reason, it's certainly a very big problem."

More information

There's more statistics on U.S. emergency department visits at the U.S. Centers for Disease Control and Prevention.