| Summary: | **Background:** Previous research demonstrated that utilization management (UM) such as prior authorization (PA) or non-formulary (NF) restrictions may reduce pharmacy costs when designed and applied appropriately to certain drug classes. However, such access barriers may also have unintended consequences. Few studies systemically analyzed the impact of major UM strategies to extended-release (ER) opioids on different types of health plans.
**Objective:** This study evaluated, from payer perspective, the impact of formulary restrictions (PA, NF, or step therapy [ST]) for branded oxycodone HCl extended release (OER) on market share, and healthcare resource utilization/costs in ER opioids patients for multiple types of health plans in the United States.
**Methods:** This retrospective, longitudinal case-control study analyzed prescription and outpatient medical claims data (2012 to 2015) for adult ER opioid patients from US plans (commercial,/Medicare, national/regional) that instituted OER PA, NF, or ST. Patients from each restricted plan (cases) were matched to patients in an unrestricted plan (controls) on key patient characteristics. ER opioid market share and healthcare resource utilization/costs for both cases and controls were evaluated for the 6-month period before and after the formulary restriction dates. A difference-in-differences (DiD) approach was utilized to evaluate change in the total per patient per month (PPPM) healthcare utilization and costs.
**Results:** The study comprised 1622 (national commercial PA), 2020 (regional commercial PA), 34 703 (national commercial ST), and 4372 (national Medicare NF) cases and equivalent number of controls. OER market share decreased after the formulary restrictions, with the national Medicare NF plan showing the greatest decrease (9.2%). DiD analyses indicated that PPPM office visit change in the PA and NF plans were non-significant (decreased by 0.1 and 0.2, P>0.05), but significant in the ST plan (increased by 0.1, P=0.0001). For most plans, no significant total monthly cost change was observed; PPPM costs decreased by $48.74 and $59.87 in ST and regional PA plans and increased by $37.90 in national NF plans (all P>0.05).
**Conclusions:** This study observed that despite reducing the market share of OER, OER formulary restrictions had negligible impact on overall ER opioid utilization, and did not result in substantial pharmacy/medical cost savings.
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