States that expanded their Medicaid programs have seen significantly higher numbers of prescriptions of the opioid addiction treatment buprenorphine, according to an analysis by the Urban Institute, a policy think tank in Washington, D.C.

Medicaid-covered buprenorphine prescriptions jumped from 1.3 million to 6.2 million between 2011 and 2018, the institute found in its analysis of the program’s State Drug Utilization Data.

More than two-thirds of the prescriptions last year — 77.2 percent — were in states that had opted for Medicaid expansion under the Affordable Care Act by early 2014, the institute found.