Efficacy - What Does Efficacy Mean?

Efficacy is the capacity to produce an effect. It has different specific meanings in different fields.

Healthcare

In a healthcare context, efficacy indicates the capacity for beneficial change (or therapeutic effect) of a given intervention (e.g. a medicine, medical device, surgical procedure, or a public health intervention).

If efficacy is established, an intervention is likely to be at least as good as other available interventions, to which it will have been compared. Comparisons of this type are typically made in 'explanatory' randomized controlled trials, whereas 'pragmatic' trials are used to establish the effectiveness of an intervention.

The concept of 'self-efficacy' is an important one in the self-management of chronic diseases because doctors and patients often do not follow best practice in using a treatment.

For instance, a patient using combined oral contraceptive pills to prevent pregnancy may sometimes forget to take a pill at the prescribed time; thus, while the perfect-use failure rate for this form of contraception in the first year of use is just 0.3%, the typical-use failure rate is 8%.

Pharmacology

In pharmacology, efficacy, refers to the maximum response achievable from a drug. It is often described by the parameter Emax.

Intrinsic activity is a relative term which describes the efficacy relative to a drug which has the highest observed efficacy.

Effectiveness refers to the ability of a drug to produce a beneficial effect. A distinction is made between 'method' effectiveness which describes the effect achievable if the drug was taken as prescribed and 'use' effectiveness which is the effect obtained under typical use circumstances when adherence is not 100%.

The widely used 'intention to treat' method of analysing clinical trials provides estimates of 'use' effectiveness which are typically biased compared with 'method' effectiveness.


This article is licensed under the Creative Commons Attribution-ShareAlike License. It uses material from the Wikipedia article on "Efficacy" All material adapted used from Wikipedia is available under the terms of the Creative Commons Attribution-ShareAlike License. Wikipedia® itself is a registered trademark of the Wikimedia Foundation, Inc.

Last Updated: Feb 1, 2011

Read in | English | Español | Français | Deutsch | Português | Italiano | 日本語 | 한국어 | 简体中文 | 繁體中文 | العربية | Dansk | Nederlands | Filipino | Finnish | Ελληνικά | עִבְרִית | हिन्दी | Bahasa | Norsk | Русский | Svenska | Magyar | Polski | Română | Türkçe
Comments
The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News-Medical.Net.
Post a new comment
Post