Did the Affordable Care Act Affect Access to Medications for Opioid Use Disorder among the Already Insured? Evidence from the Rhode Island All-payer Claims Database. 
Medicaid has been cited as an important source of access to medications for opioid use disorder (MOUD), as the populations targeted by Medicaid tend to show a high prevalence of opioid use disorder (OUD) and many state Medicaid plans offer generous coverage for buprenorphine or methadone or both of these OUD medications. Previous research suggests that state Medicaid expansions implemented starting in 2014 under the Patient Protection and Affordable Care Act (ACA) helped large numbers of OUD patients gain access to MOUD that was previously lacking. However, a potential drawback of Medicaid expansion involves the impact on individuals who are already enrolled in Medicaid when these policies are implemented. The concern is that these patients’ access to care could be impeded, as new enrollees would place added demands on a limited supply of providers of MOUD.
Using the all-payer claims database for Rhode Island (HealthFactsRI) spanning the period January 2012 through December 2015, this paper tests directly for whether incumbent (pre-2014) Medicaid enrollees in Rhode Island experienced any systematic changes in their use of buprenorphine after January 2014, the month in which the state implemented the ACA and its associated Medicaid expansion. The paper also examines changes in the number of buprenorphine prescribers in Rhode Island and in their patient loads, comparing the numbers from before and after January 2014 to gain additional insights into the ACA’s potential implications for incumbent patients.
Key Findings
- The rate of buprenorphine receipt within a stable group of Medicaid incumbents generally increased from January 2012 to December 2015, although the pace of increase was slower in the post-ACA period (January 2014 through December 2015) compared with the earlier period. However, Medicaid incumbents in cities or towns that were subject to larger influxes of new enrollees in 2014 and 2015 experienced no adverse effects in terms of their chances of receiving buprenorphine following implementation of the ACA, effects that would have been expected if new enrollees had strained the capacity of providers to dispense buprenorphine.
- Supply-side factors may help to explain the apparent lack of negative side effects of the ACA on incumbent Medicaid enrollees’ access to buprenorphine. The number of buprenorphine providers treating Rhode Island patients in the paper’s sample—both overall and the number treating Medicaid patients specifically—increased fairly steadily during the two years leading up to ACA implementation and for at least 15 months after that event, resulting in increased capacity to accommodate patient demand for buprenorphine. Also, the average number of buprenorphine patients treated per prescriber increased rapidly after January 2014, suggesting that existing providers had unused treatment capacity before the policy went into effect.
Implications
Because Rhode Island is a small state, and because each state’s implementation of the ACA and Medicaid expansion comes with its own idiosyncrasies, this paper’s results may not be generalizable to the experience of Medicaid incumbents in other states. Nevertheless, the results offer little support for claims that the ACA and Medicaid expansion hindered MOUD access for patients who were already enrolled in Medicaid.
Abstract
Previous research suggests that state Medicaid expansions implemented under the Patient Protection and Affordable Care Act (ACA) helped large numbers of patients suffering from opioid use disorder (OUD) gain access to life-saving medications, including buprenorphine. However, Medicaid expansions could have impeded access to care among individuals already enrolled in Medicaid, as new enrollees would have placed added demands on a limited supply of buprenorphine providers. Using a panel data set of medical claims from Rhode Island, we estimate the causal effects of the state’s January 2014 ACA implementation on buprenorphine receipt among incumbent (pre-ACA) Medicaid enrollees by leveraging geographic variation within Rhode Island in the intensity of treatment under the ACA. Using a difference-in-differences identification strategy, multivariate regression analysis yields no evidence that incumbent Medicaid enrollees experienced added difficulties in accessing buprenorphine as a result of the ACA, despite the fact that both Medicaid and non-Medicaid enrollment increased substantially under the policy. Supply-side factors may have helped to blunt any negative fallout, as we find that the number of buprenorphine prescribers in the state increased fairly steadily during the two years leading up to January 2014 and for at least 15 months after that date. Also, the average number of buprenorphine recipients per prescriber increased rapidly after January 2014, suggesting that providers had unused treatment capacity before the policy went into effect.