Effectiveness: Whether a drug or other treatment works in real life. Effectiveness studies of drugs look at whether they work when they are used the way that most people take them. Effectiveness means that most people who have the disease would improve if they used the treatment.
Outcome: The end result of health care practices. There are many kinds of outcomes. How long people live following a health care treatment is one kind of outcome, known as survival. Other outcomes measure the effects a treatment has on people’s lives, such as changes in their ability to function or changes in their quality of life. Outcomes also include undesirable events such as side effects of drugs. Another type of outcome is whether people needed to change to another kind of treatment.
Comparative Effectiveness: A type of health care research that compares the results of one approach for managing a disease to the results of other approaches. Comparative effectiveness usually compares two or more types of treatment, such as different drugs, for the same disease. Comparative effectiveness also can compare types of surgery or other kinds of medical procedures and tests. The results often are summarized in a systematic review.

History of the Effective Health Care Program

The Effective Health Care Program is created from the Medicare Prescription Drug, Improvement, and Modernization Act (MMA) of 2003. Section 1013 of that legislation authorizes the Agency for Healthcare Research and Quality (AHRQ) to conduct and support research with a focus on comparing the outcomes and effectiveness of different treatments and clinical approaches, as well as communicate its findings widely to a variety of audiences. The research is driven by the needs of Medicare, Medicaid, and the State Children's Health Insurance Program.

The Program received its first appropriation of $15 million.
The program releases its first comparative effectiveness report on treatment alternatives for gastric reflux disease.

Congress signals continuing recognition of the Program’s importance by doubling AHRQ’s Effective Health Care Program budget to $30 million.

The American Recovery and Reinvestment Act of 2009 (ARRA) provided additional funding, in the amount of $300 million, for comparative effectiveness research.