Erin Trish

Associate Professor,
Department of Pharmaceutical and Health Economics, School of Pharmacy,
Co-Director, Leonard D. Schaeffer Center for Health Policy and Economics,
University of Southern California

For more information, contact:

  • Dina Older Aguilar
  • Maria Salgado
  • Zoya Marriott
  • Andrew Elzinga

or any member of our senior staff.


Erin Trish is an expert in pharmaceutical and healthcare economics. Her research focuses on the intersection of public policy and competition in healthcare and pharmaceutical markets, including Medicare, the No Surprises Act, the Inflation Reduction Act (IRA), insurer and hospital market concentration, pharmaceutical pricing, and the role of pharmacy benefit managers (PBMs).

Professor Trish has served as an expert witness in multiple healthcare and life sciences matters and has both trial and deposition experience. She has provided expert testimony in arbitration and in litigation involving the False Claims Act, market allocation, and killer acquisitions. Professor Trish has also testified before the U.S. Congress and in the California State Assembly, and presented her research at numerous federal agencies, including the Federal Trade Commission (FTC) and the Congressional Budget Office.

In her research focused on the pharmaceutical industry, Professor Trish analyzes market structure, prescription drug expenditures, pharmacy networks, and firms’ financial incentives. She is a leading expert on brand and generic drug markets, PBMs, and the funding and benefit design of Medicare Part D, Medicaid, and commercial prescription drug insurance.

Professor Trish’s research addresses healthcare regulation and policy, healthcare market participants, and outcomes. Her expertise includes healthcare market concentration and vertical integration, payor-provider bargaining, out-of-network reimbursement for emergency care, commercial insurance, Medicare Advantage, and exchange market functioning.

Professor Trish publishes in leading health policy, health economics, and medical journals. Her work has appeared in the New England Journal of MedicineHealth Affairs, the American Journal of Managed Care, and the Journal of Health Economics, among others. She has won several research awards, notably the Seema S. Sonnad Emerging Leader in Managed Care Research Award, which recognizes early achievements in the field and potential for exceptional long-term contributions.

At USC, Professor Trish teaches executive-level courses in health policy and management at the Marshall School of Business. She also serves as a nonresident fellow in economic studies at the Brookings Institution.


5 Questions with Erin Trish: Surprise Billing in Healthcare


Erin Trish Coauthors Amicus Briefs for U.S. District Courts

  • “No Surprises Act—Has It Had the Impact We Expected?” 20th Annual Washington Health Law Summit, 13 December 2022
  • “Pharmacy Benefit Management (PBM) Tactics: Tough Competition or Antitrust Violation?” 2022 Antitrust in Healthcare Conference, 2 June 2022