accountable care organization (ACO)

A health provider-led organization designed to manage a patient’s full continuum of care and be responsible for the overall costs and quality of care for a defined population. Multiple forms of ACOs are possible, including large integrated delivery systems, physician-hospital organizations, multi-specialty practice groups with or without hospital ownership, independent practice associations and virtual interdependent networks of physician practices. (See Delivery System Reform chapter.)

acute care

Medical services provided to treat an illness or injury, usually for a short time. (Contrast with chronic care.)


When a person engages in an activity that can be pleasurable, such as drinking alcohol or even exercising, but the continued action becomes compulsive and interferes with ordinary life responsibilities.

administrative services only agreement (ASO)

A contract typically between an insurance company and a self-funded plan or group of providers in which the insurance or management company performs only administrative services (billing, plan design, claim processing, marketing, for example) and does not assume any risk. (Also see self-insurance.)

advanceable tax credit

A subsidy to help pay for health insurance that is available when the insurance premium is due, without having to wait until a year-end tax return is filed. (Also seeTax Credit.)

Advanced Alternative Payment Models (Advanced APMs)

Alternative payment models that place some financial risk on providers in return for greater rewards for meeting quality and cost standards. Advanced APMs are one of two value-based payment programs created under the Medicare Access and CHIP Reauthorization Act of 2015 (MACRA). To qualify as an advanced APM, a model must: require use of certified electronic health record (EHR) technology; provide payment based on quality measures comparable to those used in the Merit Based Incentive Payments System (MIPS) quality category; and bear financial risk for more than a nominal amount of monetary loss, or be a patient-centered medical home that meets certain criteria.

adverse selection

When a disproportionately high number of individuals in poorer-than-average health enroll in a health plan.

age rating bands

A way to group beneficiaries into age categories in order to determine the relative cost of health insurance premiums. Under the Affordable Care Act, the ratio of age band ratings is limited to 3:1, meaning that the oldest individuals cannot pay more than three times more in premiums than the youngest individuals do.

ambulatory care

Medical service provided on an outpatient basis (no overnight hospital stay). Services may include diagnosis, treatment, surgery and rehabilitation.

American Recovery and Reinvestment Act (ARRA)

Commonly referred to as the stimulus bill or the Recovery Act, the ARRA was an economic stimulus package enacted by Congress in February 2009 and signed into law on February 17, 2009 by President Barack Obama. The law temporarily granted higher federal matching funds for states to help with the costs of higher enrollments in Medicaid as a result of the 2007-2009 recession, and it provided financial incentives for providers to adopt health information technology systems.

annual benefit limit

Limit on the amount of claims an insurer will pay in a given year for an individual. In 2010, the ACA banned annual dollar limits for most covered health benefits on all employer-based and individual health insurance plans.

annual wellness visit (AWV)

Annual visits covered by Medicare to develop a personalized prevention plan that takes a comprehensive approach to improving health and preventing disease.

any willing provider

A requirement — typically a state law — that a managed care organization must accept any properly licensed provider willing to meet the terms of a plan’s contract, whether the organization wants or needs that provider. It is often described by managed care groups as “anti-managed care” legislation.


A request for review of a denial of coverage of a particular medical service or inadequate payment for services already received. Medicare beneficiaries have the right to appeal in either of these circumstances, whether they are enrolled in traditional Medicare or in a Medicare Advantage plan. Under the ACA, all consumers have the right to appeal decisions, including coverage denials and rescissions, made by their health plans first through the plan’s internal process and then through an outside, independent decision-maker. (Also see grievance.)