Nearly one-third of doctors in Rhode Island won’t take new patients covered by Medicaid, according to a new study that also shows the state’s reimbursement rates are among the lowest in the country.

Last year 68.9% of Rhode Island doctors were accepting patients covered by the government health insurance program for low-income people, on track with the rate nationally, according to a study by Sandra Decker, a National Center for Health Statistics economist, newly published by Health Affairs.

Across all states, Decker found that doctors were more likely to accept new Medicaid patients in states where the program’s reimbursement rates were closer to those offered by Medicare. Rhode Island’s 68.9% Medicaid acceptance rate was higher than in the two other states with especially low rates, New Jersey (40.4% acceptance) and New York (61.6%).

In an email, Decker cautioned that the difference between acceptance rates in Rhode Island and New York were not statistically significant. She also noted that her analysis showed Rhode Island’s Medicaid acceptance rate is “a little higher” than the nationwide trend would suggest it should be.

“New Jersey is really a ‘negative outlier’ more than Rhode Island is a ‘positive outlier,’” Decker told WPRI.com, because “New Jersey’s acceptance rate is even lower than one would predict based on its low fee ratio.”

The new health care law allows states to expand Medicaid to cover adults with incomes below 133% of the poverty line starting in 2014. The Kaiser Family Foundation estimates up to 53,841 more Rhode Islanders will enroll in the program by 2019 at a cost of $1.8 billion to the federal government and $100 million to the state over five years.

In addition to the Medicaid expansion, the law will begin subsidizing health coverage for others through new state-based insurance marketplaces, or exchanges. “This raises questions about the capacity of the health care workforce to meet increased demand,” Decker writes in the Health Affairs study.

Another provision of the law will boost Medicaid reimbursement rates to match Medicare’s next year and in 2014, which could mean a significant bump for providers in Rhode Island considering the historically low rates the state has paid through Medicaid.

“Prior evidence suggests that physicians’ acceptance of Medicaid patients will increase as Medicaid payment rates increase,” Decker writes in the study. “Evidence also suggests that this may increase the number of times that a Medicaid patient sees a physician and decrease the reliance on hospitals for outpatient care.”

However, she adds that the fact the rate increase is only temporary may limit its effect on doctors’ behavior.