"Now the question is whether Medicaid and private plans, which mostly still have prior authorization, will remove that requirement," she said.
Currently, 35 state Medicaid programs still require prior authorization for buprenorphine, while 40 state programs require prior authorization for some or all forms of buprenorphine-naloxone, according to the , a mental health treatment advocacy group that's working with RTI on this issue.
Indiana requires physicians to provide documentation that patients have received behavioral therapy before they can prescribe buprenorphine.
In contrast, the Medicaid programs in California, Colorado, the District of Columbia, Illinois and New Jersey cover all formulations of buprenorphine with no prior-authorization requirements, according to an analysis by the Legal Action Center that accompanied the JAMA study.
Reducing prior-authorization barriers in Medicaid would have an even larger impact than doing so in Medicare, since Medicaid is the largest single payer for addiction treatment.
In 2017, out of nearly 2 million non-elderly adults with an opioid use disorder, , according to the Kaiser Family Foundation.
"This study suggests that clear guidance from CMS could immediately and significantly reduce those barriers in the Medicaid program," Ellen Weber, vice president of health initiatives at the Legal Action Center, said in a written statement. "The imperative to increase access to care is clear and pressing."
Weber's group urged the CMS to approve state plan amendments and waiver requests only if prior-authorization requirements for buprenorphine are removed.
The CMS did not respond to a question about whether it is considering adopting a similar policy on prior authorization for medication-assisted treatment in Medicaid and private health plans.
But Alex Shekhdar, a Medicaid plan consultant, said he expects the CMS to offer additional guidance to state Medicaid programs on boosting access to medication-assisted treatment. Still, he predicted that the agency will defer to states' desire to maintain control over Medicaid drug formularies and spending.
The CMS has in a number of states to let Medicaid pay for treatment of substance use disorders in residential facilities, using buprenorphine and other medication-assisted treatment.
Shekhdar said the CMS and the states likely will study the experience with those waivers in setting future policy on prior authorization.
But Mark urged the CMS, states and health plans to move faster on lowering barriers to medication-assisted treatment.
"The rationale for keeping prior authorization is cost," she said. "But in the end, they'll actually spend more because people will have overdoses, or they'll go to the hospital with drug use-related infections."
Correction: An earlier version of this story included some incorrect percentages of Medicare Part D and Medicare Advantage prescription drug plans that required prior authorization for some drugs.