Disturbing numbers show a surge in emergency department visits, mainly among Medicaid adult populations, according to a report published today in the Journal of the American Medical Association. The researchers also found a significant jump in ED waiting times.

Recent studies have shown that an increasing number of uninsured and underinsured people use the ED, stressing the health care safety net. Lead researcher of the JAMA paper, Ning Tang, an assistant clinical professor of medicine at the University of California, San Francisco, said she is surprised by the increase in ED visits, which are about double what would be expected compared with the growth of the population.

The researchers studied data from the National Hospital Ambulatory Medical Care Survey from 1997 through 2007. EDs were classified as safety-net facilities if they provided more than 30 percent of total ED visits to people covered by Medicaid, more than 30 percent of total ED visits to uninsured individuals, or to a combined Medicaid and uninsured patient population of more than 40 percent.

Between 1997 and 2007, total annual visits to EDs increased 23 percent from about 95 million to nearly 117 million. This increase, the researchers said, is almost double what would be expected from population growth over the period. Tang calls the numbers "troublesome." And while the patient visits jumped dramatically, the number of EDs available decreased by 5 percent during this period. The median wait time in the ED increased from 22 minutes to 33 minutes over the decade studied.

What's surprising about the findings, explained Tang, is that the increase in ER visits really only applies to adults covered by Medicaid. Children with Medicaid did not visit the ER more frequently, nor did elderly patients on Medicare. Researchers can't pinpoint the reason for the increase; they'd have to look at certain populations, because there is no one reason for the surge, said Tang.

"There's something about being an adult and having Medicaid...that makes a person more likely to present to the ED," Tang said in a follow-up e-mail to DOTmed News. "We think this may be due to poor access to primary care or the quality of care they are receiving."

While Medicaid enrollment increased significantly during the time period studied, researchers adjusted for this factor and found that the increase in ED visits is due to more than just increased enrollment. Between 1997 and 2007 Medicaid enrollment jumped from 29 million to 40 million; and 2009 U.S. Census data show 60 million Americans enrolled. An additional 16 million are expected to be enrolled in Medicaid under the health care reform law, which is projected to provide coverage to a total of 34 million more people in all.

The added impact of health care reform won't help the already high ER visits, said Tang. "We think these numbers could get worse," she said, pointing out that her data only goes through 2007 - before the recession hit and more people were out of work. "Since enrollment in Medicaid continues to rise in this recession and with the new health care reform law, we are concerned that this rising enrollment will lead to more ED crowding," Tang said.

The team is now conducting research on the reasons behind these findings.

"Surveys show many physicians refuse to accept new Medicaid patients due to low reimbursement. Are they even accessing primary care?" Tang said. "If they are, do they have high quality care? Is it any different than those who are privately insured?"

These are puzzling questions on top of troubling findings concerning the nation's health care safety net for the poor. This week's JAMA also includes a commentary by Mitchell H. Katz, MD on the future of Medicaid under health care reform.