Population-Based Analyses of Healthcare Utilization and Outcomes in Users of Medical Marijuana - PROJECT SUMMARY Limited scientific consensus exists on the clinical, healthcare system, financial, or societal impact of legalization of medical marijuana (MMJ) in states. The swift changes in state policies regarding MMJ use, combined with the current national opioid epidemic, creates an impending need to better understand the clinical, pharmacological, and behavioral impact of MMJ. The state of Arkansas approved MMJ use in 2016 by individuals with select conditions, and dispensaries opened in May 2019. Unique data assets available through the Arkansas Healthcare Transparency Initiative and the Arkansas Health Data Initiative (HDI) consist of individually linked but de-identified mandatory all-payer claims, vital statistics, hospital and emergency department (ED) discharge, and state police motor vehicular crash data, along with data on individuals who qualify for MMJ use. This will be the first population-level analysis that measures clinical and adverse events in a population of MMJ users and non-users through three specific aims: Specific Aim 1: Describe demographic, geographic, socioeconomic, and clinical characteristics; healthcare utilization, adverse events (new mental health diagnoses, substance abuse/overdose, suicide, accidental injury, or MVA accidents); and opioid and benzodiazepine use among three groups: 1) individuals eligible for MMJ in Arkansas who do not obtain an MMJ card (non-cardholders) , 2) individuals who are eligible and obtain a MMJ card but do not purchase MMJ (cardholders), and 3) those who are eligible, obtain a card, and purchase MMJ (consumers). Specific Aim 2: Compare 12-month pre- and post-healthcare use and costs (inpatient and outpatient care, ED visits, and prescription medications), and adverse events between consumers and non-cardholders. As a sub-aim, we will evaluate changes in opioid and benzodiazepine utilization after commencing a course of MMJ therapy. Specific Aim 3: Examine the impact of COVID-19 on MMJ cardholder requests, MMJ purchases, healthcare use, and adverse events. This project brings together five data sources to examine the impact of MMJ on Arkansans. This includes the Arkansas All Payer Claims Database (APCD), the MMJ registry, vital statistics files, and data documenting emergency department visits and MVAs. These data are linkable at the person level which allows person-level analyses or healthcare utilization and outcomes. This will be the first population-level analysis that measures clinical and adverse events in a population of MMJ users and non-users. Results of this research will help fill the gap in scientific knowledge by determining whether MMJ use has benefits (e.g, decreased healthcare use and cost, substitution opioids and benzodiazepines) while producing no additional harm (e.g., new mental health diagnosis, MVAs) and thus inform future MMJ policy.