Expanding Medicaid to cover all legal, low-income U.S. residents might not lead to a huge spike in Medicaid medical claim rates, according to researchers with the Henry J. Kaiser Family Foundation.

The Affordable Care Act, the federal legislative package that includes the Patient Protection and Affordable Care Act and the Health Care and Education Reconciliation Act, is supposed to make Medicaid health coverage available to all legal U.S. adult residents earning less than 133% of the federal poverty level in 2014.

In 2009, an adult would have to be earning less than $14,404 per year to meet that income guideline, researchers in the Kaiser office in Washington write in a report on low-income, uninsured adults.

One concern has been that low-income, uninsured adults who are getting no health care today may have a huge, untapped need for health care services once they have Medicaid.

When the researchers looked at adults included in the federal Medical Expenditure Panel Survey who had incomes under 133% of the federal poverty level and no health coverage for at least 2 years, they found that 38% had received no medical care during the 2-year period.

About 28% of the low-income, uninsured women and 71% the low-income, uninsured men went without medical care for 2 years.

Just 7% of low-income adults who had Medicaid for 2 years went without care during that period. Low-income Medicaid enrollees used more care partly because they had Medicaid coverage and partly because they had more health problems, researchers say.

The percentage of low-income adults who said they were in poor or fair health was 6% for uninsured adults and 30% for Medicaid enrollees.

Although low-income uninsured adults are healthier than comparable Medicaid enrollees, 40% said they are in good health, rather than very good or excellent health, and “the majority of these uninsured adults do not have a usual source of care,” researchers say.

The lack of experience with preventive care will make “it important that assistance is available to help them find a primary care provider,” researchers say.