Updated

Low-income people with Medicaid health insurance are more knowledgeable about their health status and have better control over some chronic conditions, like high blood pressure, than similar people without Medicaid coverage.

The Affordable Care Act was designed to expand insurance coverage for all Americans and was to coincide with Medicaid expansion that would ensure low-income people would have coverage. But 20 states, including Alabama, Florida and Texas, have still not expanded Medicaid, leaving residents with too much income to qualify for Medicaid but too little to afford the state or federal insurance exchange.

A previous study in Oregon, where uninsured people averaged about five doctor's visits per year, found that Medicaid coverage improved mental health but not physical health. The new study included more rural parts of the country where doctor visits are less frequent and found that physical health did improve with Medicaid coverage.

"In the Oregon study, the uninsured had five contacts with a primary care physician per year," said Dr. Andrea Christopher, a fellow at Harvard Medical School, lead author of the new study.

"That was dramatically different from what I saw as a primary care physician in Boise, Idaho, when Idaho did not choose to expand," Christopher told Reuters Health by phone.

The Portland area may have a more robust safety net than other parts of the country, she said.

For the new study, the researchers used the 1999 to 2012 National Health and Nutrition Examination Surveys to compare almost 3,000 adults living below the federal poverty line without insurance coverage, and nearly 1,500 similar adults with Medicaid coverage.

Those with Medicaid were more likely to have at least one doctor's visit per year and were more often aware of and in control of their high blood pressure status. Those with Medicaid were also more aware of being overweight than those without insurance, Christopher and colleagues reported in the American Journal of Public Health.

"People who have Medicaid are better off and it's not even close," said Dr. Benjamin D. Sommers of the Harvard T. H. Chan School of Public Health and Brigham & Women's Hospital in Boston, who was not part of the new study.

But Medicaid is not a "magic bullet," Sommers told Reuters Health by phone.

There was no association with awareness or control of diabetes or high cholesterol.

"Whereas high blood pressure is relatively easy to control, diabetes is much more complicated," Christopher said.

Low-income people with diabetes may also lack access to healthy foods or outlets for exercise, she said.

"Medicaid has some limitations in its ability to truly improve access to care, including low physician reimbursement rates, and some providers do not take Medicaid patients," Christopher said.

"Some pundits point to these to say Medicaid may not be improving access and chronic disease outcomes," but being without insurance carries even more dangers, she said.

Insurance coverage "improves the stability and health of the country as a whole," Christopher said.

"The most straightforward option is for all states to expand Medicaid," Sommers said.

"Right now if you're not expanding Medicaid you are making disparities worse," he said. "I think there's a real clear public health case to be made, especially when federal government will pay," for most of Medicaid expansion, and the money has already been allocated, he said.

SOURCE: http://bit.ly/1MQ3D4Z The American Journal of Public Health, online November 12, 2015.