Portland State University. Systems Science Ph. D. Program
Wayne W. Wakeland
Date of Award
Doctor of Philosophy (Ph.D.) in Systems Science
1 online resource (xx, 331 pages)
Opioid dependence and opioid related deaths are a public health problem which the United States Centers of Disease Control have declared an epidemic. While opioid agonist therapy for opioid addiction has been accepted as the most effective treatment for opioid dependence among academics, and office based buprenorphine treatment has been available in the Unites States for over 10 years, OB buprenorphine faces many barriers to widespread adoption. Empirical data on the geographic distribution of physicians able to prescribe buprenorphine and the prescribing patterns of those physicians show considerable unevenness in access and utilization of treatment services.
Federal-level policies have recently been implemented to expand access to opioid agonist therapy, but the medium and long term impacts of these policy changes on individual outcomes, public health, and geographic access equity are not yet clear.
This dissertation compares two recent federal level policies on expanding access to buprenorphine treatment: raising the regulatory limit on the number of patients a provider can treat (implemented July, 2016), and extending prescribing privileges to nurse practitioners and physician assistants (implemented February, 2017), using an empirically supported Agent Based Simulation model. Policies are assessed by a novel, at-a-glance, quantitative access equity metric: the Spatial Potential Access Gini Index, in addition to year-end treatment utilization, opioid overdose deaths, and the amount of illicit medication diversion.
In the simulation, expanding access by increasing the patient limit did not result in more equitable spatial access, while extending prescribing to NPs and PAs increased both utilization and spatial access equity. This is likely due to empirically supported model assumptions that NPs and PAs providing primary care often serve in medically underserved areas including rural and remote regions. Extending prescribing to these practitioners opens up new treatment locations changing the spatial distribution of treatment opportunities. Changing patient limits does not change the overall spatial distribution of services, so spatial access equity does not change even if overall treatment supply gets better or worse.
The primary contribution of this work is the Spatial Potential Access Lorenz Curve and the Spatial Potential Access Gini Index, measures that aggregate individual-level Spatial Potential Access Scores commonly used in health care geography to map and identify areas of access disparity within a region. The equitability of Spatial Potential Access is calculated by using the Lorenz Curve, which is commonly used to characterize the distribution of wealth or income in a society, from which a Gini Index is calculated. The Spatial Potential Access Gini Index allows for direct comparison of complex quantitative information about the geographic distribution of supply and demand in a region with other regions, or in response to policies that impact supply or demand within the region. The measure has potential applications in simulation studies on the spatial allocation of services, allowing equity assessment of policy alternatives, as well as in empirical work, allowing equity comparisons of different regions, or in hybrid studies in which policy experiments are conducted on data-rich maps.
Nielsen, Alexandra Elizabeth, "Quantifying Spatial Potential Access Equity in an Agent Based Simulation Model of Buprenorphine Treatment Policy in the United States" (2018). Dissertations and Theses. Paper 4516.