Surgery patients covered by Medicaid generally enter the hospital for their surgeries in worse health, do worse afterward, stay in the hospital longer and find themselves back in the hospital more often than surgical patients covered by private insurance, according to a new study by researchers at the University of Michigan School of Medicine.

In addition, people with Medicaid coverage were twice as likely as privately insured patients to have a number of health risk factors prior to surgery, many more emergency operations, two-thirds more complications after surgery and use 50 percent more hospital resources. The Medicaid patients in the study were also, on average, younger than the privately insured patients studied and twice as likely to smoke. They had higher rates of conditions that can result from poor health habits and make surgery riskier, including diabetes, lung disease and blockages in their blood vessels.

The researchers gathered their data from a one-year study of patients in 52 Michigan hospitals looking at 1,400 patients aged 18 to 64 using Medicaid or private insurance.

The findings are very important in the near term, say the study authors, because Medicaid has been expanded this year for millions of low incomes people in 26 states under the Affordable Care Act. Previous studies show that many of the newly insured under Medicaid are likely to seek out medical care they’ve delayed because of a lack of funds, including surgeries. The findings are also financially significant for hospitals who care for many patients receiving Medicaid benefits. Often, hospitals don’t make back their full expenditures on Medicaid patients. Information on the cost implications of admitting Medicaid patients for surgery can give them an idea of expenses over the next several years, especially since Federal Medicaid dollars are expected to decline over the next few years.

“If we make the presumption that the new Medicaid-covered patients will fit the mold of what we see now, surgical and inpatient teams must be prepared to provide the care and support they need,” says Seth Waits, M.D., a University of Michigan surgical resident who led the study.

The study was published in JAMA Surgery.