Use of and Steering to Pharmacies Owned by Insurers and Pharmacy Benefit Managers in Medicare.

Importance: The prevalence of pharmacies owned by integrated insurers and pharmacy benefit managers (PBMs), or insurer-PBMs, is of growing regulatory concern. However, little is known about the role of these pharmacies in Medicare, in which pharmacy network protections may influence market dynamics. Objective: To evaluate the prevalence of insurer-PBM-owned pharmacies and the extent to which insurer-PBMs steer patients to pharmacies they own in Medicare. Design, Setting, and Participants: This cross-sectional study used Medicare Part D claims data on prescription fills for a 20% random sample of US beneficiaries enrolled from January 1 through December 31, 2021. Data were analyzed from March to November 2024. Exposures: Prescription fills. Main Outcomes and Measures: The main outcome was the share of spending filled by insurer-PBM-owned pharmacies overall, by pharmacy type (specialty and nonspecialty), and by drug class. For the top 100 specialty and nonspecialty molecules by claim volume, 2 quantities were identified for 4 major insurer-PBMs (Cigna, CVS, Humana, and UnitedHealth Group): share of the index firm's insurer claims filled by its owned pharmacies and share of other firms' insurer claims filled by the index firm's owned pharmacies. Differences between these quantities were assessed to evaluate the degree to which insurer-PBMs steered patients to their own pharmacies. Results: Among 10 455 726 patients (54.8% women; mean [SD] age, 71.8 [10.7] years), 34.1% of all pharmacy and 37.1% of specialty pharmacy spending occurred through Cigna, CVS, Humana, or UnitedHealth Group pharmacies. Among specialty molecules, market shares varied by drug class (antivirals: 18.5%; antipsychotics: 29.5%; cancer: 32.5%; disease-modifying antirheumatic drugs: 41.1%; multiple sclerosis: 64.8%; pulmonary arterial hypertension and idiopathic pulmonary fibrosis: 89.7%). Across molecule-firm combinations, a 19.8 (95% CI, 18.0-21.6)-percentage point and 13.9 (95% CI, 13.1-14.7)-percentage point greater share of claims were filled at insurer-PBM-owned pharmacies than would be expected without steering for specialty and nonspecialty categories, respectively. Conclusions and Relevance: This cross-sectional study found that insurer-PBM firms represented an important portion of the Medicare Part D market, especially for certain drug classes, and that insurer-PBM firms steered patients to their own pharmacies, despite certain pharmacy network protections in Medicare. These findings underscore the need to understand the impacts of insurer-PBM and pharmacy integration on medication access and costs for Medicare patients.