Improving geographic access to methadone clinics.

INTRODUCTION: Opioid misuse is a nationwide public health crisis. Methadone treatment is proven to be highly successful in preventing opioid use disorder, reducing the use of illicit drugs, and preventing overdoses. Clients acquire methadone daily from clinics, making geographic access crucial for the initiation of and adherence to treatment.

METHODS: This work estimates unsatisfied methadone demand due to lack of geographic access at a census tract level and models the problem of identifying optimal locations to open new methadone clinics. The objective function of the model is a weighted combination of providing access to individuals with unmet methadone demand and improving the travel time of individuals currently attending a clinic. Data on existing methadone clinics and statewide methadone demand is acquired from Substance Abuse and Mental Health Services Administration (SAMHSA) surveys from 2019. Unsatisfied demand is estimated through a linear regression model after aggregating the population, heroin use, and satisfied methadone demand at the state level.

RESULTS: Nationwide, we find 18.2 % of the United States population does not have geographic access to a methadone clinic and estimate 77,973 individuals in these areas would attend a clinic if geographic access barriers were removed (95 % CI: 67,413-88,532). In a case study of six Midwestern states, we find that geography significantly contributes to the value of opening additional clinics and we see large differences in expected gains between states sharing similar characteristics such as population and satisfied methadone demand. The number of additional clients served by opening one new clinic ranges from 180 to 804 across these six states, representing between 8.4 % and 16.2 % of state unmet demand. Between 1.2 % and 14.1 % of existing clients were reassigned with a single newly opened clinic, with a one-way average travel distance improvement between 6.3 and 11.9 miles / person / day for these clients.

CONCLUSIONS: The results demonstrate the large unserved methadone demand in the United States, the significant improvement in methadone access for new and existing clients that can be achieved by opening new clinics, and the important role state-specific geography plays in these decisions.