(AP) — A research report says states can combat rising prison health care costs by expanding Medicaid under the Affordable Care Act, outsourcing and other measures.

The report released Tuesday by Pew Charitable Trusts says that correctional health care spending in the 42 states examined grew by an average of 52 percent between 2001 and 2008.

The report relied on numbers from the federal Bureau of Justice Statistics, The year 2008 was the most recent available.

Researchers listed four ways that states could reduce those costs, including Medicaid expansion. Under that method, health care inside prison walls wouldn’t be covered but treatment provided to prisoners at hospitals would be eligible for reimbursement.

Critics of expansion say states shouldn’t transfer the responsibility for prisoner care to the federal government.