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Table 1 Key terms and definitions for the scale-out of an evidence-based intervention (EBI)

From: “Scaling-out” evidence-based interventions to new populations or new health care delivery systems

Key term Definition
Scale-up The deliberate effort to broaden the delivery of an EBI with the intention of reaching larger numbers of a target audience. Often an EBI scale-up will target health delivery units within the same, or very similar settings, under which the EBI has already been tested.
Scale-out A deliberate effort to broaden the delivery of an EBI. Scale-out is an extension of scale-up and uniquely refers to the deliberate use of strategies to implement, test, improve, and sustain an EBI as it is delivered to new populations and/or through new delivery systems that differ from those in effectiveness trials. There are three types of scale-out, each indicating the extent to which the EBI is delivered to new populations and/or through new delivery systems.
Type I scale-out: population fixed, different delivery system A type of scaling-out wherein an EBI is scaled-out to the same population as previously tested, but through a different delivery system.
Type II scale-out: delivery system fixed, different population A type of scaling-out wherein an EBI is scaled-out to a different target population through the same delivery system as previously tested.
Type III scale-out: different population and delivery system A type of scaling-out wherein an EBI is scaled-out to a different target population, through a different delivery system, than previously tested.
Borrowing strength Utilizing empirical evidence from a previous EBI effectiveness trial in combination with new evidence from a scale-out trial to test EBI effectiveness when moving it to a new population and/or through a new delivery system. Borrowing strength allows for a more limited evaluation, typically prioritizing implementation outcomes, that takes less time and expense to conduct than the original effectiveness trial.
Intervention adaptation Modifications to an EBI to facilitate its feasible, practical, and acceptable implementation in new contexts.
External validity The representativeness or generalizability of an effect.
Core elements Prototypical and/or necessary activities or components of an EBI. When scaling-out an EBI to a new population and/or through a new delivery system, core elements of the EBI should be retained to ensure its effectiveness.
  1. EBI evidence-based intervention