Medicare Advantage Premiums Higher in Markets with Concentrated Health Plans

As health care costs continue to consume an increasingly large share of the federal budget and impact Americans’ personal finances, it is important to understand the various drivers of those costs. The literature documents how higher levels of concentration (lack of competition) among commercial payers and providers contributes to higher premiums for commercial health plans. Less well understood, however, is the relationship between the concentration of Medicare Advantage (MA) plans in a market and MA premiums. Our paper uses a fixed-effects, multivariate regression to evaluate the association of both MA plan concentration and health system concentration on MA premiums. We found that increased concentration (lower competition) in the MA insurance market was associated with higher MA premiums and that if all beneficiaries were in markets at least as competitive as the average market today, they would pay nearly $200 million less in annual premiums. We also found that the highest premiums were in markets that lacked competition among MA payers and hospital markets, suggesting the interaction between MA insurer concentration and hospital system concentration matters. Our findings suggest that maintaining or increasing current levels of competition is necessary for controlling MA premiums.