(HealthDay)—Medicaid expansion to include substance use disorder (SUD) treatment does not guarantee access, particularly in underserved and rural counties, according to a study published online Dec. 25 in JAMA Psychiatry.

Janet Cummings, Ph.D., from Emory University in Atlanta, and colleagues examined data from the 2009 National Survey of Substance Abuse Treatment Services and the 2011 to 2012 Area Resource file. All 50 states were included in the examination of sociodemographic factors tied to county-level access to SUD treatment facilities.

The researchers found that 60 percent of U.S. counties have at least one outpatient SUD facility that accepts Medicaid. This rate is lower in many Southern and Midwestern states, compared to other areas of the nation. Having a higher percentage of black, rural, and/or uninsured residents in a county is associated with a lower likelihood of having one of these facilities.

"The potential for increasing access to SUD treatment via Medicaid expansion may be tempered by the local availability of facilities to provide care, particularly for counties with a high percentage of black and/or uninsured residents and for rural counties," the authors conclude.