Diminishing Insurance Choices In The Affordable Care Act Marketplaces: A County-Based Analysis.

While the Affordable Care Act has expanded health insurance to millions of Americans through the expansion of eligibility for Medicaid and the health insurance Marketplaces, concerns about Marketplace stability persist-given increasing premiums and multiple insurers exiting selected markets. Yet there has been little investigation of what factors underlie this pattern. We assessed the county-level prevalence of limited insurer participation (defined as having two or fewer distinct participating insurers) in Marketplaces in the period 2014-18. Overall, in 2015 and 2016 rates of insurer participation were largely stable, and approximately 80 percent of counties (containing 93 percent of US residents) had at least three Marketplace insurers. However, these proportions declined sharply starting in 2017, falling to 36 percent of counties and 60 percent of the population in 2018. We also examined county-level factors associated with limited insurer competition and found that it occurred disproportionately in rural counties, those with higher mortality rates, and those where insurers had lower medical loss ratios (that is, potentially higher profit margins), as well as in states where Republicans controlled the executive and legislative branches of government. Decreased competition was less common in states with higher proportions of residents who were Hispanic or ages 45-64 and states that chose to expand Medicaid.