Project Summary Drug overdose deaths that have included opioids have increased so rapidly over the past six years that the average life expectancy in the United States has declined. The national drug overdose rate for adults aged 65 and over increased by 7% from 2015 to 2016. Older adults may be at higher risk for opioid-related deaths and hospitalizations because they are more likely to start treatment for chronic pain and are also at higher risk for physical dependence. In 2017 the most commonly reported reason for opioid misuse in adults 50 and older was “relative physical pain”. In 2018, 80% of Americans with opioid use disorders (OUD) received no treatment; older adults are particularly disadvantaged. This despite the fact that medications for the treatment of opioid use disorder (MOUD) are an effective form of treatment. In 2017, 35 percent of substance use disorder (SUD) treatment facilities accepted Medicare as payment. Additionally, lack of geographic access to SUD treatment facilities is a broad problem with 85 percent of counties in the U.S. lacking a treatment center with an opioid treatment program. For older adults, access challenges may be exacerbated as approximately 25 percent of Americans older than age 65 live in a small town or other rural area; a rate that is higher than for younger adults. Rural areas also tend to have fewer SUD treatment facilities and higher rates of overdose. The data typically used to track the supply of licensed SUD treatment facilities– the National Survey of Substance Abuse Treatment Services– do not contain measures on the use of MOUD by providers at the facility nor does it contain geographic identifiers below the state. The overall objective of this R21 is to increase understanding of MOUD use by providers at SUD treatment facilities; whether variation in MOUD use at SUD facilities is associated with disparities in treatment for older adults; and how policies to improve access affect health care utilization among older adults. Our specific aims are to: Aim 1: Identify sociodemographic and geographic disparities in MOUD use for Medicare beneficiaries receiving OUD treatment in SUD treatment facilities. Aim 2: Identify disparities in health care utilization outcomes, including ED and inpatient care for overdoses, associated with SUD treatment facilities’ MOUD use rates. Aim 3: Evaluate the effect of state policies associated with OUD treatment on MOUD use rates for beneficiaries receiving treatment in SUD treatment facilities. The proposed R21 is a necessary first step to creating data linkages between a novel dataset of SUD treatment facilities, their providers, and claims data. We use the combined dataset to understand the use of MOUD by these facilities in the treatment of OUD for Medicare beneficiaries. Based on our results, in a future R01 we hope to develop the first ever OUD quality of care measures for older adults at treatment facilities.