Poor, Chronically Sick, Unemployed Most Likely to Lose Coverage if ACA Repealed, Study Finds The demographics of who's most at risk of losing health care coverage.

 -- With Republican lawmakers promising to repeal and replace the Affordable Care Act under the new administration, researchers have been working to understand how people who gained coverage after the ACA's passage will be affected.

Those most at risk for losing coverage are more likely to be poor, have a chronic illness or be unemployed, according to a study published today in JAMA Internal Medicine.

The groups more likely to lose coverage also visited their doctors more often, according to the study, which examined demographic data of people who had coverage or tax credits thanks to ACA provisions.

Dr. Pinar Karaca-Mandic, lead author of the study, told ABC News that the goal was get hard data on the people who would be affected by a repeal of the ACA.

"This is not a simulation exercise," Karaca-Mandic said. "We used data from the National Health Interview Survey."

Approximately 20 million people have gained health care coverage after the ACA was passed in 2010, according to the study.

Currently, 10.4 million individuals have private insurance policies acquired through an exchange. Of these individuals, 84 percent had incomes that were 400 percent of the federal poverty level. Individuals who make less than 400 percent of the federal poverty level are eligible for tax credits to help pay for health insurance. The federal poverty level income is $11,880 for an individual and $24,300 for a family of four.

It remains unclear if repealing the ACA and replacing it with an alternate plan will imperil these individuals coverage in the future, the study authors said.

The researchers from multiple institutions, including the University of Minnesota School of Public Health, examined federal data to understand who would be affected if the tax credits provided by the ACA were stopped and Medicaid expansion was repealed.

To understand the demographics of the people who would be affected by a repeal of the ACA, researchers looked at three cohorts of financial status. These cohorts were adults who get tax credits because they made less than 400 percent of the federal poverty level, childless adults who became eligible for Medicaid coverage after the ACA's passage, and parents or caretakers enrolled in Medicaid whose income was between 50 to 139 percent of the federal poverty level.

The people most likely to be affected by an ACA repeal were minorities, the poor, unemployed people and people with chronic medical conditions, researchers found. They also found that these people were more likely to have been to an emergency room at least once or have seen a doctor 10 or more times in the previous year.

Christine Eibner, an economist and professor at Pardee RAND Graduate School in Santa Monica, California, who has conducted other research on the ACA, said the new JAMA study echoes past predictions on who would be affected by a repeal of the ACA.

"It substantiates the model estimates," Eibner told ABC News. "This takes actual data and looks at who was enrolled."

Dr. Darien Sutton-Ramsey is an emergency medicine physician at Bellevue Hospital in New York. He is a resident in the ABC News Medical Unit.