Figure 1. Opioid Policy Model Schematic Showing Transition Between Different Health States.

The state-level Opioid Policy Model consists of 4 categories of health states representing subpopulations at different stages of opioid use: (1) prescription opioid misuse, (2) illicit opioid use, (3) opioid use disorder (OUD), and (4) in recovery. Individuals can enter the model over time with either prescription opioid misuse or illicit opioid use and may subsequently develop OUD. Those with OUD can transition to the in-recovery state, starting the recovery process typically through treatment initiation. Individuals in recovery remain at risk of relapse, returning to the OUD state. We assume that those who are no longer receiving medications for opioid use disorder (MOUD) must relapse before receiving MOUDs again. All individuals in the model who are actively using opioids have a risk of opioid overdose death that depends on their health state, and all individuals have a background mortality risk from other (ie, nonopioid-related) causes (transition not shown in figure for simplicity). Deaths (from opioid overdose or from other causes) are possible from all states.