This report is a part of a series of studies that examine the impact of drug formularies in five states (Arkansas, California, Indiana, Kentucky, and New York) that implemented formularies in 2018 and 2019. As of January 1, 2023, 17 states have adopted drug formularies, with several other states considering implementation. Findings of this study should therefore be of interest to stakeholders in California as well as those in other states considering implementation of drug formularies in their jurisdictions. 

In this study, we examine the impact of California’s workers’ compensation drug formulary on prescription drug utilization and costs using detailed transaction data for prescriptions filled between January 1, 2016, and March 31, 2021, by workers within 12 months of injury. California’s Medical Treatment Utilization Schedule (MTUS) drug formulary went into effect on January 1, 2018. 

Monitoring Trends after Adoption of California’s Drug Formulary. Vennela Thumula and Te-Chun Liu. March 2023. WC-23-22.