In Qato et al’s study published in JAMA, researchers “analyzed PBM market concentration separately for commercial insurance, Medicare Part D, and Medicaid managed care in the US.”
They analyzed every prescription filled in the US in 2023 and observed 5 PBMs’ market share and concentration by payer type (commercial insurance, Medicare Part D, and Medicaid managed care). Along with the Big 3 PBMs, researchers also included the market share data of MedImpact and SS&C Health. Finally, using the Herfindahl-Hirschman Index (HHI), they determined that HHI scores above 1800 were defined as “highly concentrated markets.”1
After analyzing a total of 14 billion prescriptions across 91 different PBMs, researchers found the PBM market to be considered highly concentrated with an overall score of 1972, 172 points above the researchers’ “highly concentrated” threshold.
“The degree of concentration varied by payer type; the HHI was lowest in commercial insurance (1940), with 90 PBM participants, and highest in Medicare Part D (2399), with 21 PBM participants. CVS Caremark, Optum Rx, and Express Scripts accounted for 73.6% of retail prescriptions overall, yet their shares varied by payer type,” they wrote.1
Indeed, each of the Big 3 PBMs’ highest percentage of market share varied across all 3 markets. For CVS Caremark, its largest share was in the Medicaid managed care market at 39.2%; Express Scripts’ largest share was in the commercial market at 28%; and Optum Rx’s largest share was held in the Medicare Part D market at 27.7%.
However, at 73.6% of the total market share, the 3 largest PBMs still carry immense power across all 3 types of payer markets. Despite researchers’ data not matching that of other PBM reports—such as the Federal Trade Commission’s recent report that the Big 3 PBMs control 79% of the entire prescription drug market—a plethora of recent findings are similar across the board and highlight the need for slowing down vertical integration and PBM market consolidation.3
“These findings underscore the importance of considering payer-specific concentration when evaluating PBMs’ anticompetitive practices, as the 3 top PBMs may be pursuing different market strategies. The dominance of a few large PBMs across all payers and a smaller PBM (SS&C Health) in Medicare Part D alone has important antitrust implications. These findings could inform federal policies, including proposed legislation that would prohibit unfair and deceptive PBM business activities and the Federal Trade Commission’s ongoing investigation of PBM anticompetitive practices,” concluded authors of the study.1
READ MORE: FTC Issues First Report Regarding Ongoing PBM Inquiry
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References
1. Qato DM, Chen Y, Van Nuys K. Pharmacy benefit manager market concentration for prescriptions filled at US retail pharmacies. JAMA. Published online September 10, 2024. doi:10.1001/jama.2024.17332