Erin Trish

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

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Education

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 (NSA), the Inflation Reduction Act (IRA), insurer and hospital market performance, pharmaceutical pricing, and the role of pharmacy benefit managers (PBMs).

Expert testimony in litigation, arbitration, and before Congress and federal agencies

Professor Trish has served as an expert witness in multiple life sciences and healthcare matters and has both trial and deposition experience. She has provided expert testimony in arbitration and in litigation involving the False Claims Act, price fixing and market allocation, killer acquisitions, and the 340B drug pricing program.

In addition, Professor Trish has 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 (CBO). She has coauthored amicus briefs in several matters involving the NSA.

Research on public policy and competition in healthcare and pharmaceutical markets

In her work 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, 340B, and the funding and benefit design of Medicare Part D, Medicaid, and commercial prescription drug insurance.

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

Publications, awards, and academic appointments

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 and undergraduate- and graduate-level courses in pharmaceutical and health economics at the Mann School of Pharmacy and Pharmaceutical Sciences and Price School of Public Policy.

Event

2026 Antitrust in Healthcare Conference

Collections

340B Drug Pricing Program

Event

ASHEcon 2025: The Annual Conference of the American Society of Health Economists

Article

5 Questions with Erin Trish: Surprise Billing in Healthcare

Case

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