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clinical effectiveness, efficacy*
Effectiveness is the extent to which a treatment has desirable effects; i.e. reduces undesirable [outcomes?outcome] or increases desirable outcomes. Sometimes, the term effectiveness is used to indicate specifically the desirable effects of treatments under usual or everyday conditions, as measured in pragmatic trials. Efficacy is sometimes used to indicate the desirable effects of treatments under ideal conditions, as measured in explanatory trials. However, efficacy is also commonly used as a synonym for effectiveness. Because of this, the meaning of “efficacy” is often unclear and we recommend against using that term. In addition, pragmatic and explanatory trials can differ in a variety of ways and to different extents.
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