Wayne Kepner
Postdoctoral Scholar, Psychiatry
Bio
Wayne Kepner, PhD, MPH is a public health researcher whose scholarship focuses on health disparities and substance use among vulnerable populations. Dr. Kepner is currently a T-32 Post-doctoral Fellowship in Pain and Substance Use at Stanford University's School of Medicine, where he will continue his research under the mentorship of Dr. Keith Humphreys and Dr. Mark McGovern.
Dr. Kepner received his doctoral degree from the Joint Doctoral Program in Interdisciplinary Research on Substance Use at San Diego State University and the University of California, San Diego. His research focused on substance use disorders, health services utilization, and geospatial analysis of health data, with a particular emphasis on older adult populations. Dr. Kepner has extensive experience in both qualitative and quantitative research methods, having conducted interviews with older adults on cannabis use and analyzed large-scale electronic health records. He has co-authored several peer-reviewed publications on topics ranging from cannabis use trends to emergency department utilization for substance-related diagnoses. In addition to his academic work, Dr. Kepner is committed to community engagement, co-founding Aztecs For Recovery, a collegiate recovery program at SDSU.
Stanford Advisors
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Keith Humphreys, Postdoctoral Faculty Sponsor
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Mark McGovern, Postdoctoral Research Mentor
All Publications
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Three trajectories of implementation of medications for opioid use disorder in primary care.
Addiction science & clinical practice
2025; 20 (1): 69
View details for DOI 10.1186/s13722-025-00600-y
View details for PubMedID 40887602
View details for PubMedCentralID 11060908
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U.S. State Marijuana and Delta-8-Tetrahydrocannabinol Laws and Delta-8-Tetrahydrocannabinol Use.
American journal of preventive medicine
2025: 108026
Abstract
Delta-8-tetrahydrocannabinol has gained popularity since the passage of the 2018 U.S. Farm Bill. The absence of federal laws and varying state regulations governing delta-8-tetrahydrocannabinol have allowed manufacturers to evade restrictions placed on marijuana products. This study examined delta-8-tetrahydrocannabinol use across different state marijuana and delta-8-tetrahydrocannabinol policies.A cross-sectional, web-based survey of 1,523 U.S. adults was conducted in October-November 2023. Responses were weighted to represent the national adult population. Inverse-probability-of-treatment weights balanced covariates across policy groups; adjusted risk ratios and 95% CIs were estimated in 2025 for state (1) marijuana policy (prohibited, medical only, recreational) and (2) delta-8-tetrahydrocannabinol policy (prohibited, regulated, unregulated).Approximately 7.7% (95% CI=6.5, 9.1) of U.S. adults reported using delta-8-tetrahydrocannabinol in their lifetime. The prevalence of delta-8-tetrahydrocannabinol use was lower among adults in states permitting recreational marijuana use (5.5%; adjusted risk ratio=0.48, 95% CI=0.33, 0.70) and lower in states permitting medical use only (8.5%; adjusted risk ratio=0.73, 95% CI=0.46, 1.14) than in states prohibiting all marijuana use (10.9%). Adults in states that regulated (3.9%; adjusted risk ratio=0.33, 95% CI=0.20, 0.55) or prohibited (4.5%; adjusted risk ratio=0.47, 95% CI=0.28, 0.78) delta-8-tetrahydrocannabinol sales reported lower rates of delta-8-tetrahydrocannabinol use than adults in states with unregulated markets for delta-8-tetrahydrocannabinol (10.5%).Delta-8-tetrahydrocannabinol use is more common where marijuana remains prohibited and less common where delta-8-tetrahydrocannabinol sales are regulated or prohibited. State-level restrictions targeting delta-8-tetrahydrocannabinol appear to reduce use, suggesting that closing regulatory gaps could limit consumption of these products.
View details for DOI 10.1016/j.amepre.2025.108026
View details for PubMedID 40900067
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Effectiveness of Mutual Help Groups for Illicit Drug Use Disorders: A Review of the Current Literature (vol 12, 12, 2025)
CURRENT ADDICTION REPORTS
2025; 12 (1)
View details for DOI 10.1007/s40429-025-00659-2
View details for Web of Science ID 001482920800001
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Effectiveness of Mutual Health Groups for Illicit Drug Use Disorders: A Review of the Current Literature
CURRENT ADDICTION REPORTS
2025; 12 (1)
View details for DOI 10.1007/s40429-025-00635-w
View details for Web of Science ID 001416151400002
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Effectiveness of Mutual Help Groups for Illicit Drug Use Disorders: A Review of the Current Literature.
Current addiction reports
2025; 12
Abstract
Evaluate literature examining whether mutual help groups (MHGs) for illicit drug use disorders benefit participants.Recent studies consistently show that MHG attendance and involvement predict reductions in drug use and addiction severity. More rigorous methodologies offer stronger evidence of effectiveness, but additional controlled trials are needed. Drug-focused MHG challenges include lower success rates of professionally-delivered interventions to facilitate participation compared to alcohol-focused MHGs, and stigma towards opioid agonist medications. Culturally-tailored MHG formats may benefit specific populations (e.g., racial/ethnic minorities). Non-12 step MHGs like SMART Recovery show promise, but research is limited. Online delivery formats positively affect retention.Evidence on the benefits of MHGs for drug use disorders is encouraging but incomplete. MHG engagement may be enhanced by cultural adaptations and reduced stigma towards medications. Future research should focus on non-12 step MHGs, treatment integration, optimizing online formats, and understudied groups (e.g. Indigenous populations). Selection bias remains a challenge in evaluations of MHG effectiveness.
View details for DOI 10.1007/s40429-025-00635-w
View details for PubMedID 40831571
View details for PubMedCentralID PMC12360454
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Emergency care utilization in persons with substance related diagnoses.
Addictive behaviors reports
2024; 20: 100573
Abstract
Substance use is a significant contributor to emergency department (ED) visits. Little is known about ED utilization patterns of individuals with substance related diagnosis (SRD). We used electronic health records (EHR) from a large healthcare system in California to examine ED healthcare utilization and socio-demographic characteristics of individuals with SRDs.We used EHR data on all adult patients in our health system from April 2012 through September 2019 to conduct adjusted logistic regression models to determine socio-demographic correlates of SRDs (e.g., use, misuse, dependence) and associations between having an SRD and receiving emergency care.Among the sample (n = 342,651), the majority were female (55.08 %), Non-Hispanic White (58.10 %), with mean age of 48.26 (SD = 18.10), and there were 18,015 (5.26 %) individuals with an SRD. Patients with an alcohol-related diagnosis had the highest odds of visiting the ED (aOR = 3.75), followed by those with opioid (aOR = 3.57) and stimulant-related diagnoses (aOR = 3.48). Individuals with an SRD were more likely to identify as male, Black/African American, Hispanic/Latinx, have no health insurance, and have a serious mental illness. In the adjusted model, those with an SRD were significantly more likely to have ever received emergency care (aOR 3.72 [95 % CI 3.62-3.84]) than those without an SRD.Our study found an association between having an SRD and utilizing emergency health services. Demographic characteristics suggest disparities exist for those with SRDs around gender, race/ethnicity, insurance status, and mental health. These data can help with screening and targeted responses to prevent or provide emergency care.
View details for DOI 10.1016/j.abrep.2024.100573
View details for PubMedID 39687706
View details for PubMedCentralID PMC11647655