Date of Award
1-1-2025
Document Type
Thesis
Degree Name
M.S. in Pharmaceutical Science
First Advisor
John Bentley
Second Advisor
Sujith Ramachandran
Third Advisor
Kaustuv Bhattacharya
School
University of Mississippi
Relational Format
dissertation/thesis
Abstract
Background: Authorized generics (AGs) are essentially brand-name drugs without the brand name on their labeling. AGs are often marketed as cost-saving alternatives to brand-name drugs; however, their impact on patient out-of-pocket (OOP) expenditures compared to independent generics (IGs) remains understudied, especially within Medicare. This study investigates the OOP costs of AGs versus IGs among Medicare beneficiaries with Part D coverage.
Methods: A cross-sectional analysis was conducted using the 5% national sample of Medicare Part D claims data from 2012 to 2020, linked with the FDA’s NDC Directory data to specify Authorized Generics, Independent Generics, and Brands. The study compared OOP costs (per claim, per unit dispensed, and per day supply) for AGs and IGs when both were simultaneously available in the market. The Wilcoxon rank-sum test was used to assess cost differences between IGs and AGs overall and within different dispensing years, therapeutic classes, and dosage forms. Multivariable linear regression was employed to estimate adjusted mean OOP cost differences, controlling for benefit phase and Medicare plan. Sensitivity analyses were performed by winsorizing high outlier OOP costs.
Results: IGs increasingly dominated the market (74.16% of prescriptions filled in 2012 to 84.78% in 2020), while AG utilization remained marginal (3.65% in 2012 to 2.30% in 2020). AGs consistently demonstrated higher median OOP costs across all measures, including per claim ($3.404 vs. $2.417), per unit dispensed ($0.094 vs. $0.043), and per 1-day supply ($0.106 vs. $0.065). This cost difference widened over time and persisted across most therapeutic classes and dosage forms. Multivariable linear regression, adjusting for potential confounders, demonstrated consistent findings; that is, significantly lower OOP costs for IGs compared to AGs (p<0.0001). The adjusted mean differences were $4.31 less per claim, $0.29 less per unit dispensed, and $0.21 less per 1-day supply for IGs relative to AGs.
Conclusion: Medicare Part D beneficiaries consistently incur higher OOP costs for authorized generics compared to independent generics. These findings highlight the need for greater transparency and strategic formulary management to optimize generic utilization and minimize OOP costs, thereby improving medication affordability and access for older adults and individuals with disabilities.
Recommended Citation
Arabshomali, Arman, "Comparative Analysis of Out-of-Pocket Expenditures on Authorized Generics and Independent Generics Among Medicare Beneficiaries" (2025). Electronic Theses and Dissertations. 3231.
https://egrove.olemiss.edu/etd/3231