6: Overview of Intervention Delivery

Overview of Intervention Delivery

Carefully designed health interventions, if not delivered as planned, may not induce the desired changes that mediate its effects on the ultimate outcomes. A successful delivery of an intervention rests on applying its components by carrying out the respective activities, in the selected mode, and at the specified dose. For most health interventions, a successful delivery is the responsibility of both (1) the health professionals (also referred to as providers, therapists, interventionists) entrusted the provision of the intervention, and (2) the clients (also referred to as persons and patients in practice, and participants in research) exposed to the intervention and expected to carry out the treatment recommendations.

The intervention theory plays an important role in informing the delivery of the intervention. In particular, elements of the theory of implementation, integrated into the intervention theory and depicted in the logic model (Nelson et al., 2012), guide the specifications of: (1) what is needed in terms of human and material resources, and contextual features, to facilitate the interventionists’ and clients’ performance of the intervention activities and treatment recommendations, respectively; (2) what are the intervention’s specific and nonspecific components, and how they are operationalized into content to be conveyed, activities to be performed by the interventionists and clients during the intervention sessions as well as the treatment recommendations to be carried out by clients in daily life; and (3) how the components are delivered, in what sequence, where, when, and for how long (as explained in Chapters 4 and 5).

To inform the provision of the intervention, the specifications are captured in the intervention protocol or manual. The manual is a document that lists, for each session, the content or topics to be covered, the activities to be performed, and the treatment recommendations for clients to apply in daily life (also called homework) (see Chapter 7). Interventionists are trained (see Chapter 8) and requested to adhere to the manual in order to deliver the intervention with fidelity or integrity. Fidelity means that the intervention is provided as conceptualized (in the intervention theory) and operationalized (in the intervention manual), that is, as intended, designed, or planned. Delivering the intervention with fidelity is essential to initiate its mechanism of action that is responsible for generating the expected improvement in the ultimate outcomes.

Despite extensive efforts at enhancing the delivery of health interventions with fidelity, in research and practice, variations in delivery are highly likely. The variations are introduced by the interventionists and/or the clients, for different reasons. The variations reduce the capacity of the intervention to initiate the mechanism of action and, consequently, its effectiveness in research and practice. In this chapter, possible variations in intervention delivery are described and their impact on the validity of inferences regarding the interventions’ effectiveness is discussed. The importance of monitoring fidelity and strategies for promoting fidelity of intervention delivery are introduced. Key points in the fidelity‐adaptation debate are highlighted.


Variations in the delivery of a health intervention occur at different levels and for several reasons. The variations can take place when the researchers or health professionals engage in the operationalization of the intervention, when the interventionists actually provide the intervention, and when clients or participants apply the intervention. Possible reasons for these variations are presented next.

6.1.1 Variations in Operationalization of Interventions by Researchers

Researchers and health professionals, independently or collaboratively, engage in operationalizing the intervention’s active ingredients that are identified in the intervention theory. This involves the specification of the components and the development of each component’s content, activities, and treatment recommendations (see Chapter 4 and 5). Variations can happen in the operationalization process (Haynes et al., 2016). These variations are reflected in some discrepancy between the intervention’s active ingredients as identified in the theory and the components operationalizing them. In other words, the components, specified in terms of content, activities, and treatment recommendations, are not fully in alignment with the active ingredients. This lack of correspondence between the conceptualization and operationalization of the intervention poses a major threat to construct validity of the intervention in that the components, as operationalized, may reflect active ingredients of other (than intended) health interventions. For instance, Keller et al. (2009) reviewed reports of studies that evaluated behavioral interventions to promote physical activity. They found examples of interventions that fell short of incorporating components or activities to promote achievement of the desired changes in key mediators, such as self‐efficacy, of improvement in the ultimate outcomes, that is, engagement in physical activity.

Possible reasons for variations in the operationalization of health interventions include:

  1. Lack of clarity or comprehensiveness in the conceptualization of the health problem and incomplete analysis of the problem that result in the misspecification of its potentially modifiable aspects. The misspecification contributes to the selection of active ingredients that either address the incorrectly identified aspects of the problem or are incongruent with the intended aspects of the problem (which were inaccurately understood).
  2. Limited publication of conceptual knowledge about health interventions, reflected in the theories underpinning them. The limited knowledge presents challenges in delineating the active ingredients that comprise the interventions and in putting them into operation.
  3. Scant description of the intervention in published reports, making it difficult to identify the active ingredients of the intervention, and to understand how they are operationalized and delivered (e.g. Abraham et al., 2014; diRuffano et al., 2017).
  4. Limited experience in the systematic process for designing interventions and/or in generating the intervention theory necessary to inform the operationalization of the intervention.
  5. Limited time available for theorizing and analyzing the correspondence between the conceptualization and operationalization of the intervention due to social, political, or other types of pressure to find solutions to emerging pressing health problems.

6.1.2 Variations in Delivery of Interventions by Interventionists

Although the importance of fidelity is well recognized and its maintenance is emphasized, the chances for variations in the delivery of health interventions, in research and practice, are high. Emerging evidence indicates that interventionists do not fully adhere to the manual when providing interventions in research. A moderate level of adherence has been consistently reported (Hardeman et al., 2008; Toomey et al., 2019), implying that interventionists perform about 50% of the activities comprising the intervention components. Similarly, health professionals do not follow the manual when implementing interventions in practice. It is estimated that less than 50% of health professionals (also called healthcare or service providers, clinicians, practitioners) provide the evidence‐based interventions with fidelity, even after training (Wiltsey‐Stirman et al., 2015).

Nonadherence to the intervention manual results in variations with which the intervention is delivered to participants in research and clients seen in practice. The variations can take two general forms: adaptations of the intervention’s components and/or mode and dose of delivery, and drifts represented in inconsistent delivery of the intervention across participants or clients. Adaptations and drifts are commonly observed in research and practice (DeRosier, 2019; Roscoe et al., 2019). They are often made by interventionists or health professionals delivering the intervention, usually without consultation with the intervention’s designers or without reference to the intervention theory and relevant theoretical propositions that guide adaptations (Masterson‐Algar et al., 2014; Wiltsey‐Stirman et al., 2015). Adaptations

Adaptations of the intervention entail modifications to the intervention. The modifications may be extensive so that what clients are exposed to deviates from what is originally designed or planned. The modifications may include:

  1. Adding a new specific component; integrating a specific component from other established interventions; or removing a component (Pérez et al., 2016; Wiltsey‐Stirman et al., 2015): These modifications result in a combination of components that are not congruent with changes or adaptations of the active ingredients proposed in the intervention theory. Thus, the intervention as delivered is incongruent with the intervention as designed. This type of adaptation is a threat to construct validity because there is lack of clarity about what exactly is provided to clients and, consequently, what actually produced the intended outcomes.
  2. Adding or removing a nonspecific component (e.g. providing feedback) to the intervention: These modifications may not alter the active ingredients but may affect the support that clients need to successfully carry out or enact the treatment recommendations and hence, benefit from the intervention.
  3. Use of a different mode for delivering the intervention than the one specified in the intervention theory: This change may impact the size of the intervention effects, as reported in systematic reviews of health interventions. The results indicate that the size of the interventions’ effects varies by mode of delivery. For instance, the effect sizes of behavioral therapies for insomnia were smaller with technology‐based (self‐help modules) delivery than face‐to‐face group sessions (e.g. van Straten et al., 2018).

Some adaptations of the intervention are made intentionally and formally. This is often done to adapt a generic approach to treatment to a particular health problem or client population including clients of diverse cultural background. For example, cognitive behavioral therapy is a generic approach that has been adapted for the management of insomnia and depression. These adaptations are systematically and carefully done to ensure correspondence of the intervention components with its active ingredients as specified in the intervention theory, while altering specific content, activities, or mode of delivery to accommodate the unique experience of the health problem and/or the characteristics of, the target client population.

Other adaptations of the intervention are not carefully planned, but made for different reasons. These tend to be encountered in several situations:

  1. When the intervention is not well defined, its active ingredients are not clearly and explicitly specified: This situation leaves much room for variability in the interpretation of what the intervention comprises and therefore, its operationalization into specific components. In this case, the interventionists or health professionals may use their own frame of reference, expert knowledge or expertise, in articulating the active ingredients of the intervention, specifying its components, and delivering them. This results in deviation of what is provided from what is intended or planned, and variations in what different providers with different frame of references do and convey to clients in different contexts. For example, the intervention “provide psychological support” could be interpreted as any or a combination of the following activities: listen to the client, encourage the client to ventilate his or her feelings, or give positive feedback.
  2. When the intervention manual is either not available or its content is not presented in a lucid way: In this situation, there is limited guidance for delivering the intervention. Thus, interventionists or health professionals do not have a clear description of the intervention content to convey and activities to perform, to use as a reference when delivering the intervention. Therefore, they may improvise and drift from what is intended.
  3. When the interventionists or health professionals (1) do not have the qualifications required for delivering the intervention, such as expert knowledge of the health problem and the intervention techniques (Lewis et al., 2019) and (2) do not receive adequate training in the theoretical underpinnings of the intervention and in the process for implementing correctly its components: In this case, interventionists or health professionals do not have the cognitive knowledge and the practical skills to successfully deliver the intervention as planned, leading to less‐than‐optimal or drifts in performance. Alternatively, providers with the required qualifications and mastery of the intervention protocol may modify components, content, or activities to fit with their expertise (Wiltsey‐Stirman et al., 2015). Furthermore, those with unfavorable perceptions of the intervention may make adaptations that are in alignment with their views or beliefs of what would be the most appropriate therapeutic approach or method for the clients.
  4. When the resources and the contextual features needed for optimal delivery of the intervention are not readily available: In this situation, interventionists or health professionals are forced to adapt the intervention activities and mode of delivery to be consistent with what is present or can be afforded in local settings. For instance, it may be challenging to provide cognitive behavioral therapy for insomnia in face‐to‐face sessions in rural remote areas due to the geographical dispersion of providers and clients. In this case, video or teleconferencing is a viable alternative mode of delivery.

The adaptations, if not carefully planned, may alter the intervention in a way that impacts its capacity in initiating the mechanism of action underlying its effects on the ultimate outcomes. Drifts

Drifts involve inconsistency in the delivery of the intervention, whereby what the interventionists or health professionals provide varies across clients within or across practice settings. Therefore, clients are exposed to different components, content, activities, and treatment recommendations. Drifts may involve:

  1. Customizing some aspects of the intervention to the characteristics, concerns, circumstances, or preferences of individual clients.
  2. Loosening the structure of the intervention, whereby more time is permitted to discuss a topic of particular interest to clients, even if the topic is not within the scope of the intervention.
  3. Temporarily deviating from the specific components of the intervention (Wiltsey‐Stirman et al., 2015).

Drifts are exemplified with flexibility in delivering the cognitive behavioral therapy for insomnia in a group format. For instance, an interventionist may engage clients with cancer in a discussion of their experience of stress. The discussion, although unplanned, is necessary to address the clients’ emotional needs. After all, the discussion is beneficial because stress is a determinant of poor sleep.

Drifts are more commonly encountered than adaptations in research and practice. When delivering standardized interventions, drifts are frequently related to the interventionists’ or health professionals’ perception of the importance of individualizing treatment; this consists of tailoring some intervention’s content, activities, and/or treatment recommendations to the personal profile and life circumstances of clients. Many health professionals are socialized to value person or client‐centered care, which involves attending to people’s individual needs, collaborating with people to plan care, and providing care that is responsive to people’s needs and preferences (Sidani & Fox, 2014). They consider tailoring as an essential element of practice that defines high‐quality care (e.g. Aggarwal et al., 2014). Accordingly, health professionals are inclined to drift away from the planned standardized intervention, modifying its content, activities, and treatment recommendations in an attempt to be responsive to clients’ needs and life circumstances. They view such modifications as critical to demonstrate understanding and sensitivity to clients, which is the building block for initiating and maintaining a trusting relationship and a working alliance with clients. The relationship is the foundation for clients’ satisfaction with, adherence to, and effectiveness of interventions (Waller, 2009).

When delivering tailored interventions in‐person, drifts may happen if the customization process is not clearly articulated. In tailored interventions, interventionists or health professionals individualize aspects of the intervention to be responsive to clients’ characteristics, based on a well‐delineated algorithm, which consists of a set of decision rules. When these rules are not explicit or well described, providers are left with minimal guidance to structure the customization process. They are not clear on: what client characteristics to assess, when, how; how to interpret the results of the assessment; and what intervention component, content, activity, treatment recommendation, or mode of delivery to select. As a result, what is tailored and how it is tailored vary across clients.

When providing standardized or tailored interventions via technology‐based modes, drifts may occur if the planned content and activities are not clearly presented and explained, with the potential of misinterpretation.

Drifts affect the reliability of the intervention delivery. This inconsistency is associated with variability in outcome achievement.

6.1.3 Variations in Application of Interventions by Clients

Clients are equal partners in the implementation of health interventions. They are expected to (1) attend the planned intervention sessions or review all modules for full exposure to the intervention components; (2) engage in the activities proposed for each session (e.g. discussion of barriers to skill performance) or module (e.g. set goals); and (3) enact or adhere to the treatment recommendations in daily life, correctly and consistently.

Variations in clients’ attendance at sessions, engagement in the planned activities, and enactment of treatment recommendations are prevalent in research and practice. These variations are exemplified in situations when clients attend some but not all sessions or review some modules, carry out a select number of treatment recommendations, or inappropriately perform the recommendations. Variations in clients’ implementation of the intervention are related to a wide range of reasons, including but not limited to:

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Nov 28, 2021 | Posted by in NURSING | Comments Off on 6: Overview of Intervention Delivery
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