Health Insurance Instability and Mortality Among Patients Receiving Bup Tx for OUD

The goal of this multi-site observational cohort study is to link electronic health records (EHR) with novel data sources to examine insurance instability and its association with all-cause and overdose mortality in adult patients who received medications for opioid use disorder (MOUD). The main objectives of the study are: * Objective 1. Perform data linkage of a cohort of patients who received MOUD with the National Death Index using a probabilistic algorithm for matching records to ascertain fact and cause of death relative to treatment and insurance status. * Objective 2: Assess the association of insurance instability and risk of death, including all-cause mortality and drug- and alcohol-related overdose mortality.