Skip to main content
eScholarship
Open Access Publications from the University of California

UC Berkeley

UC Berkeley Previously Published Works bannerUC Berkeley

Differing Impacts Of Market Concentration On Affordable Care Act Marketplace Premiums

Abstract

Recent increases in market concentration among health plans, hospitals, and medical groups raise questions about what impact such mergers are having on costs to consumers. We examined the impact of market concentration on the growth of health insurance premiums between 2014 and 2015 in two Affordable Care Act state-based Marketplaces: Covered California and NY State of Health. We measured health plan, hospital, and medical group market concentration using the well-known Herfindahl-Hirschman Index (HHI) and used a multivariate regression model to relate these measures to premium growth. Both states exhibited a positive association between hospital concentration and premium growth and a positive (but not statistically significant) association between medical group concentration and premium growth. Our results for health plan concentration differed between the two states: It was positively associated with premium growth in New York but negatively associated with premium growth in California. The health plan concentration finding in Covered California may be the result of its selectively contracting with health plans.

Many UC-authored scholarly publications are freely available on this site because of the UC's open access policies. Let us know how this access is important for you.

Main Content
For improved accessibility of PDF content, download the file to your device.
Current View