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Glossary of Terms

We know that many of the concepts used on this site can be difficult to understand. For that reason, we have provided you with a glossary to help you make sense of the terms used in Comparative Effectiveness Research. Every word that is defined in this glossary should appear highlighted throughout the Web site. When you come upon a highlighted term and would like to read the full definition, you can either click on the word to visit the glossary or roll your mouse over the word for a pop-up definition.

 

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Efficacy

Definition: Whether a drug or other treatment works under the best possible conditions. In a research study about efficacy, the study participants are carefully selected, and the researchers can make sure the drug is taken properly and stored properly. The study participants may differ from other people in the general public who have the disease. A treatment that has efficacy under the best conditions may not work as well in a different group of people with the same disease.

Example: For example, a recent clinical trial compared people treated with insulin to people treated with oral medicine for diabetes. Only people with no other medical problems were enrolled in the study, and most were under age 65. The people treated with insulin had better improvement in their blood glucose than the people treated with oral medicines. This study is considered an efficacy study, because only younger people without any other health problems were included. Many people who have diabetes are over age 65 and have other problems such as heart disease. It is not known whether the same results would be found in these people.

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