Mathematical/Computational Virology & Medicine
Modeling the impact of spatial inequities in access to medications for treatment of opioid use disorder among persons who inject drugs
Eric Tatara, Qinyun Lin, Jonathan Ozik, Marynia Kolak, Nicholson T Collier, Dylan Halpern,
Luc Anselin, Harel Dahari, Basmattee Boodram, John Schneider
Background: Access to treatment and medication for opioid use disorder (MOUD), such as methadone, is essential for improving health outcomes by reducing infection and overdose risks associated with injection drug use. MOUD resource distribution, however, is often a complex interplay of social and structural factors that result in nuanced patterns reflecting underlying social and spatial inequities. Persons who inject drugs (PWID) that receive MOUD treatment experience a reduction in the number of daily drug injections and a reduction in the number of syringe sharing episodes with other individuals. We assessed the impact on reduction in syringe sharing behaviors among PWID who are adherent to methadone treatment via simulation studies.
Methods: Actual (real-world) and counterfactual scenarios of varying levels of social and spatial inequity to providers of methadone were evaluated using HepCEP, a validated agent-based model of syringe sharing behaviors among people who inject drugs (PWID) in metropolitan Chicago, Illinois, U.S.A. Synthetic spatial distributions reflecting disparate geographic patterns of methadone provider location and population characteristics are evaluated to show how population-level health outcomes vary accordingly.
Results: For all methadone access assumptions and provider location distributions, redistributing methadone providers results in some areas with poor access to MOUDs. All scenarios exhibited some areas with poor access, highlighting the scarcity of providers in the region as a major challenge. Need-based distributions are more like the actual provider distribution, indicating that the actual spatial distribution of methadone providers already reflects the local need for MOUD resources.
Conclusions: The impact of the spatial distribution of methadone providers on syringe sharing frequency is dependent on access. When there are significant structural barriers to accessing methadone providers, distributing providers near areas that have the greatest need (as defined by density of PWID) is optimal.