The main outcomes in effectiveness research are health outcomes, asking “does the thing improve health?” Implementation research focuses instead on how much or how well people and places do the thing. Examples of implementation outcomes include the percentage of clinicians delivering the thing, the percentage of eligible patients receiving thing, the extent to which clinicians are following the guideline for the thing, or even the skill with which clinicians deliver the thing.

In a landmark moment for the field, Dr. Enola Proctor and colleagues published Outcomes for Implementation Research: Conceptual Distinctions, Measurement Challenges, and Research Agenda, distinguishing implementation outcomes from service system outcomes and clinical treatment outcomes.

Implementation outcomes are the effects of deliberate and purposive actions to implement new treatments, practices, and services and are conceptually distinct from the other two types of outcomes. Implementation outcomes serve three key functions as:

Proctor et al (2011) Implementation Outcomes Definitions^*

Acceptability: The perception among implementation stakeholders that a given treatment, service, practice, or innovation is agreeable, palatable, or satisfactory.

Adoption: The intention, initial decision, or action to try or employ an innovation or evidence-based practice. Adoption also may be referred to as “uptake.”

Appropriateness: The perceived fit, relevance, or compatibility of the innovation or evidence-based practice for a given practice setting, provider, or consumer; and/or perceived fit of the innovation to address a particular issue or problem. “Appropriateness” is conceptually similar to “acceptability,” and the literature reflects overlapping and sometimes inconsistent terms when discussing these constructs. We preserve a distinction because a given treatment may be perceived as appropriate but not acceptable, and vice versa.

Cost: The financial impact of an implementation effort. The true cost of implementing a treatment depends upon the costs of the particular intervention, the implementation strategy used, and the location of service delivery.

Feasibility: The extent to which a new treatment, or an innovation, can be successfully used or carried out within a given agency or setting. Typically, the concept of feasibility is invoked retrospectively as a potential explanation of an initiative’s success or failure, as reflected in poor recruitment, retention, or participation rates. While feasibility is related to appropriateness, the two constructs are conceptually distinct.

Fidelity: The degree to which an intervention was implemented as it was prescribed in the original protocol or as it was intended by the program developers. Fidelity has been measured more often than the other implementation outcomes, typically by comparing the original evidence-based intervention and the disseminated/implemented intervention in terms of (1) adherence to the program protocol, (2) dose or amount of program delivered, and (3) quality of program delivery.

Penetration: The integration of a practice within a service setting and its subsystems. From a service system perspective, the construct is also similar to “reach” in the RE-AIM framework.

Sustainability: The extent to which a newly implemented treatment is maintained or institutionalized within a service setting’s ongoing, stable operations.

^{* Proctor E, Silmere H, Raghavan R, Hovmand P, Aarons G, Bunger A, Griffey R, Hensley M. Outcomes for implementation research: conceptual distinctions, measurement challenges, and research agenda. Adm Policy Ment Health. 2011 Mar;38(2):65-76. doi: 10.1007/s10488-010-0319-7. PMID: 20957426; PMCID: PMC3068522.}