This post is a slightly modified version of one by Austin Frakt and Ian Crosby that originally appeared at Kaiser Health News last week. Full references have been added for academic papers cited.
It is well known that concentration in the health insurance industry is to blame for rapidly rising premiums. Well known, but wrong. Taking political advantage of this common misconception, last week the House passed a bill to repeal insurers’ antitrust exemption. But even if that bill becomes law it won’t do much good, and politicians’ distraction could actually harm consumers. It’s far more likely that premium increases are largely due to other factors.
Those who claim that the antitrust exemption is the main reason a few insurers have substantial market power don’t understand the narrowness of that exemption’s scope. The law at issue, the McCarran-Ferguson Act, shields most aspects of “the business of insurance” from federal (but not state) antitrust oversight. This means that only those insurer activities dealing directly with providing insurance–think underwriting risk, setting rates, defining benefits, and the like–are not ordinarily subject to federal antitrust scrutiny.
There are exempt insurance practices that, at least in theory and under certain conditions, could help insurers defend and expand their market share against competitors. But the exemption simply does not shield the most straightforward kinds of conduct that make companies big.
Activities not connected with the basic risk-spreading function of insurance are deemed “the business of insurers” rather than “the business of insurance” under the law, and do not enjoy any federal antitrust exemption. Thus mergers and acquisitions among health insurers are as aggressively (or passively) scrutinized as those in any other industry by federal antitrust enforcers.
Health care reform advocates concerned about the high degree of concentration in today’s insurance market cite the more than 400 mergers among health plans allowed over the last 13 years. But repeal of the McCarran-Ferguson antitrust exemption would have literally no effect on this trend. Even if other forms of stepped-up antitrust enforcement or other means of encouraging competition were to have a material impact on insurer market power, there is little reason to believe it would produce tangible benefits for consumers absent parallel efforts targeting the provider side of the market.
While there is some evidence that insurers’ market concentration plays a role in premium increases, that role is small. For example, a National Bureau of Economic Research paper  found that only 2.1 percent of employer-sponsored health insurance premium increases between 1998 and 2006 were due to insurer concentration.
It is far more plausible that a high proportion of premium increases are due to a combination of concentration in the provider market and adverse selection, especially in the nongroup market. After all, most premium dollars are not kept by insurers and go toward payment of health care services . Insurers take a little off the top, but not enough to be blamed for anything like the perennially large rate increases.
A recent Health Affairs paper  describes the upward pressure on costs driven by provider organization and concentration. Based on hundreds of interviews with representatives of hospitals, physician organizations, health plans and other stakeholders in six California health care markets, the authors conclude that “[t]he shift in who holds the upper hand in negotiating payments—once held by health insurance plans but now resting with health care providers—has had a major impact on California premium trends.” And we all know what those trends have looked like lately.
Perhaps counter-intuitively, large insurers can be bulwarks against high costs driven by provider consolidation. Two papers [4, 5] by health economists in the International Journal of Health Care Finance and Economics indicate that the high degree of market power held by insurers acts as a counterweight to that held by hospitals. Therefore, diluting the insurance market may have small downward effects on insurer profit and administrative costs, but it could have large upward effects on prices of health care services. Those higher prices would be passed on to consumers.
That’s why those who understand our health care system know that costs will not be tamed by a focus on the insurance market alone. The Congressional Budget Office has scored the likely effect on premiums of health insurer antitrust repeal as insignificant. Therefore, concentration among providers, and in particular hospitals, must also be addressed.
Don’t get us wrong–we don’t think that the current antitrust exemption is good law or policy. But cracking down on insurer market power without doing the same against providers may well have the opposite of its intended effect. Taming health care costs will be hard. Attacking insurers is, by comparison, very easy, as well as popular. But in this case, what is popular will not be particularly effective.
 L Dafny, M Duggan, and S Ramanarayanan (2009). Paying a premium on your premium? Consolidation in the U.S. health insurance industry. NBER Working Paper 15434.
 L Dafny, K Ho, and M Varela. (2010). Let them have choice: Gains from shifting away from employer-sponsored health insurance and toward an individual exchange. NBER Working Paper 15687.
 R Berenson, P Ginsburg, and N Kemper. (2010). Unchecked provider clout in California foreshadows challenges to health reform. Health Affairs Web Exclusive, February 25.
 R Feldman and D Wholey. (2001). Do HMOs have monopsony power? International Journal of Health Care Finance and Economics 1(1).
 L Bates and R Santerre. (2008). Do health insurers possess monopsony power in the hospital services industry? International Journal of Health Care Finance and Economics 8(1).