Examining patterns of opioid overdose hotspots and opioid treatment deserts in California - Enter the text here that is the new abstract information for your application. This section must be no longer than 30 lines of text. Opioid use disorder (OUD) has proven to be a debilitating and deadly disease. Vulnerable populations including the homeless; racial and ethnic minority groups; people in poverty; and rural residents often bear the highest burden. Previous research suggests that localized sub-county analyses are necessary to understand the patterns and determinants of opiate overdoses. However, most local public health departments do not have the resources to laboriously collect, clean, and analyze the required data. We aim to provide sub-county analyses of opioid overdose hotspots and opioid treatment deserts that will reveal actionable patterns for California public health officials to directly address their county’s needs. Specific Aims: (1) to use emergency medical services data from 2022-2024 to detect opioid overdose hotspots using SaTScan and Bayesian spatial modeling, (2) to use emergency medical services and treatment center location data to map opioid treatment deserts defined by long travel times to treatment centers, and (3) to apply qualitative research methods with local OUD treatment providers to identify additional local determinants of hotspots and treatment deserts not obvious from quantitative analyses of population-level data. We will use advanced data processing and visualization to contextualize our conclusions about the link between hotspots; treatment deserts; and the social, economic, and environmental determinants of health. These relevant and easily comprehendible dashboards will lend themselves directly to resource allocation, policy changes, and development of targeted interventions. The training plan provides the skills needed for the fellowship applicant to begin a successful career as an independent investigator in translational public health research on opioid use disorder. He will undertake training in clinical opioid use and treatment; advanced geospatial methods and modeling; and qualitative methods to apply and tailor research findings for public health impact. The candidate will be mentored by faculty from across disciplines including epidemiology, psychiatry, data science, geospatial analyses, and statistics. Dr. Nelson, the primary sponsor, leads the T32 training grant in behavioral, social, and population health research that the candidate will continue to benefit from, and a fellow T32 director at Emory University, Dr. Waller, will serve an important mentoring role for the application of advanced geospatial analyses. Other mentors include leading researchers in opiate addiction from the Department of Psychiatry Drs. Humphries and McGovern; two social epidemiology research mentors Drs. Rehkopf and Kiang; and a health psychologist specializing in qualitative methods and citizen science Dr. King. Through this fellowship, the applicant will advance translational methods in opioid use disorder, receive training and mentorship from world-class sponsors and collaborators, and be prepared for independent public health research in his postdoctoral work.