Volume 54 | Number 5 | October 2019

Abstract List

Emily R. Adrion MSc, PhD


To examine the relationship between insurer market structure, health plan quality, and health insurance premiums in the Medicare Advantage () program.

Data Sources/Study Setting

Administrative data files from the Centers for Medicare and Medicaid Services, along with other secondary data sources.

Study Design

Trends in market concentration from 2008 to 2017 are presented, alongside logistic and linear regression models examining plan quality and premiums as a function of insurer market structure for 2011.

Data Collection/Extraction Methods

Data are publicly available.

Principal Findings

plans that tend to operate in more concentrated markets have a higher predicted probability of receiving a high‐quality health plan rating. Operating in more concentrated markets was also found to be associated with higher premiums. Among plans that tend to operate in very concentrated markets, high‐quality plans were associated with premiums as much as two times higher than premiums associated with lower‐quality plans.


Any policies directed at enhancing insurer competition should consider implications for health plan quality, which may be very different than the implications for enrollee premiums.