Even before the Affordable Care Act was close to passing, it was clear that immigrants illegally living in the country would not be part of many of the law’s benefits. They are not allowed to buy health insurance from the online marketplaces, at least in part because opponents argued that these immigrants overburden emergency rooms and hospitals. But a study released Monday finds that they’re less likely to use health services than U.S. citizens and other immigrants here legally.

Using 2009 data from the California Health Interview Survey, the researchers found that 11 percent of adults living illegally in California had visited a hospital emergency room in the past year, a rate significantly lower than the 20 percent of U.S. born adults in California. That “negates the myth that undocumented immigrants are responsible for [emergency department] overcrowding,” the researchers wrote in the latest issue of the journal Health Affairs. They noted little difference among children’s ER visits.

However, that was not true about children’s doctor visits. Ninety percent of U.S.-born children had at least one doctor visit in the preceding year, while only 78 percent of the children in the state illegally did. Naturalized citizens and immigrants in the state legally also had significantly higher rates than those without proper authority.

The survey “does not explicitly inquire about undocumented status,” researcher write, so they “developed a model to estimate California’s “undocumented immigrant population.”

‘You Wait And Wait Until Something Forces You To Go’

Mammography and colorectal cancer screening rates were also significantly lower among the adults here illegally compared to their U.S.-born counterparts or other immigrants who have permission to be in the country.

“When you don’t have the resources, money or there’s a language barrier, you’re not going to go for your annual checkup or cancer screenings,” said Nadereh Pourat, lead author for the study and director of research for the University of California Los Angeles’ Center for Health Policy Research. “You wait and wait until something forces you to go.”

Undocumented immigrants comprise 6.8 percent of California’s population but make up 24 percent of the state’s uninsured population.

Pourat said the researchers also found even when immigrants who are in the country illegally have insurance, they use fewer health services than other immigrants with insurance. She said that could be caused by their fears of revealing their immigration status, the language barrier, and out-of-pocket costs. Pourat said allowing these immigrants access to the marketplaces will not only help be healthier but it will also save them money because they are more likely to deal with health problems earlier and perhaps in a less expensive way.

“One or five doctor visits costs much less than one emergency room visit,” Pourat said.

The decision to keep these immigrants out of the health insurance marketplaces, also known as exchanges, may also hurt the hospitals and other health care providers serving large numbers of low-income and uninsured patients, the study suggests. Federal funding for those safety-net facilities is being cut back. Some of the newly insured may move to more traditional sources of care, leaving these facilities with an overload of immigrants who are in the state illegally. Much of the care for those people may be uncompensated and could be unpopular, the researchers point out.

“If a community health clinic is only left with undocumented immigrants to treat, politically that could be a charged issue,” Pourat said.