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Policy Research

The Division of Economic and Health Policy Research undertakes independent research and data analyses to produce unique AMA socioeconomic advocacy resources, such as the AMA’s Competition in Health Insurance study and AMA Policy Research Perspectives, for use by AMA physician leaders and staff, the Federation, physician members, and policymakers. The Division also conducts economic analyses and develops advocacy resources (e.g., SGR “gap” chart, state-level impacts, budget scoring analyses) in direct support of AMA federal, state, and private sector advocacy agendas (e.g., Medicare/SGR reform; medical liability reform, antitrust reform). The following reports come from this AMA unit and/or other AMA units working on key advocacy topics.


The Price Effects of a Large Merger of Health Insurers: A Case Study of United Health-Sierra

By José R. Guardado, David W. Emmons and Carol K. Kane

Published in Health Management, Policy and Innovation, 1(3) 16-35, July 2013.

In this paper, we examine the association between market concentration and prices in the health insurance industry. Specifically, we conduct a case study of a large merger between health insurers— UnitedHealth Group and Sierra Health Services—which caused a shock to market concentration in Nevada's health insurance markets. Using a novel data set on health plan attributes, we exploit that natural experiment to obtain estimates of the association between the merger and premiums. The treatment group consists of health plans in markets affected by the merger, and the control group consists of health plans in similar markets that were not affected. Using a difference-in-difference propensity score matching estimator, we compare the change in premiums of health plans in the treatment group to the premium change in the controls. We find that premiums in Nevada markets increased by 13.7 percent after the merger relative to the control group. Our findings suggest that the merging parties exploited the market power gained from the merger.

Competition in health insurance: A comprehensive study of U.S. markets, 2014 Update

The 2014 Update to Competition in Health Insurance: A Comprehensive Study of U.S. Markets presents new data on the level of competition in health insurance markets across the United States. It is intended to help researchers, policymakers and federal and state regulators identify areas where consolidation among health insurers may cause anticompetitive harm to consumers and providers of care. The Department of Justice (DOJ) and Federal Trade Commission (FTC) use this type of information to assess the anticompetitive effects of horizontal mergers between firms.

Using 2012 data from HealthLeaders-Interstudy—the most comprehensive source of data on enrollment in HMO, PPO, POS and CDHP health plans—we report the two largest insurers' commercial market shares and concentration measures (HHIs) for 388 metropolitan areas, the 50 states and the District of Columbia.

Among the key findings is that 72 percent of the 388 metropolitan areas were highly concentrated (HHI>2,500). Additionally, in 90 percent of the metropolitan areas, one or more insurers had a combined HMO+PPO+POS market share of 30 percent or more, and in 41 percent of the areas, at least one insurer had a share of least 50 percent.

These findings should prompt federal and state antitrust authorities to vigorously examine the competitive effects of proposed mergers between health insurers in the future.

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Competition in health insurance: A comprehensive study of U.S. markets, 2013 Update

Competition in health insurance: A comprehensive study of U.S. markets, 2012 Update

Health Spending
Medical Liability Reform
Medical Practice