Deductible: The amount that the insured must pay out-of-pocket before the health insurer pays its share. For example, policy-holders might have to pay a $500 deductible per year, before any of their health care is covered by the health insurer. It may take several doctor's visits or prescription refills before the insured person reaches the deductible and the insurance company starts to pay for care. Furthermore, most policies do not apply co-pays for doctor's visits or prescriptions against your deductible.
The US health insurance market is highly concentrated, as leading insurers have carried out over 400 mergers from the mid-1990s to the mid-2000s (decade). In 2000, the two largest health insurers (Aetna and UnitedHealth Group) had total membership of 32 million. By 2006 the top two insurers, WellPoint (now Anthem) and UnitedHealth, had total membership of 67 million. The two companies together had more than 36% of the national market for commercial health insurance. The AMA has said that it "has long been concerned about the impact of consolidated markets on patient care." A 2007 AMA study found that in 299 of the 313 markets surveyed, one health plan accounted for at least 30% of the combined health maintenance organization (HMO)/preferred provider organization (PPO) market. In 90% of markets, the largest insurer controls at least 30% of the market, and the largest insurer controls more than 50% of the market in 54% of metropolitan areas. The US Department of Justice has recognized this percentage of market control as conferring substantial monopsony power in the relations between insurer and physicians.
Network-based plans may be either closed or open. With a closed network, enrollees' expenses are generally only covered when they go to network providers. Only limited services are covered outside the network—typically only emergency and out-of-area care. Most traditional HMOs were closed network plans. Open network plans provide some coverage when an enrollee uses non-network provider, generally at a lower benefit level to encourage the use of network providers. Most preferred provider organization plans are open-network (those that are not are often described as exclusive provider organizations, or EPOs), as are point of service (POS) plans.