DELIVERING INTERVENTIONS
6.3 INTERVENTION FIDELITY
inconsistent engagement and enactment of the intervention by clients, result in var- iations in clients’ experience of improvement in the outcomes. Clients exposed to the full intervention (i.e. all its components, as designed) given in the selected mode and at the optimal dose demonstrate the expected pattern of change in the out- comes. Clients who receive some components in the same or different mode and at a less‐than‐optimal dose show limited improvement in the outcomes. Clients provided a few, if any, components in various modes and at a minimal dose level exhibit no change in the outcomes. Increased variability in the levels of outcome improvement, reported by clients assigned to the intervention group, dilutes the effectiveness of the intervention and reduces the statistical power to detect significant intervention effects (Ibrahim & Sidani, 2015; Stokes & Allor, 2016). The intervention is claimed ineffective. This conclusion is potentially erroneous (type III error) because the observed ineffectiveness is due to inconsistent and/or inappropriate delivery of the intervention (Rixon et al., 2016).
6.2.3 Impact on External Validity
Variations in the delivery of the intervention limit external validity. If not made explicit, the variations affect the replicability of the intervention’s effects in different research and practice contexts (Campbell et al., 2013; O’Shea et al., 2016; Toomey et al., 2019). With the variations, it would be difficult to (1) determine the active ingre- dients, reflected in the specific components, that should be provided when the inter- vention is delivered by different interventionists and health professionals, to different clients, in different settings in order to replicate the intervention’s effects on the desired outcomes; (2) identify the intervention’s specific and nonspecific components, as well as mode of delivery, that could be modified in order to fit with the characteristics of the client population in different contexts; (3) delineate the most appropriate way to make these modifications without jeopardizing the intervention’s integrity and effectiveness; and (4) specify the dose range that is associated with desired changes in the outcomes. This type of information is important to guide the translation and implementation of the intervention in practice.
In summary, variations in the delivery of an intervention by interventionists and health professionals and its implementation by clients can lead to inaccurate conclu- sions about its effectiveness. Therefore, it is essential to attend to the fidelity with which an intervention is provided.
6.3 INTERVENTION FIDELITY
The terms fidelity, integrity, and adherence have been used interchangeably (see Chapter 9) to refer to the extent to which an intervention is delivered as intended, planned, or originally designed (Berkel et al., 2019; Forsberg et al., 2015; French et al., 2015; Haynes et al., 2016; Toomey et al., 2019; Wojewodka et al., 2017). The concern is whether the interventionists and health professionals provide the inter- vention components; convey the content and the treatment recommendations; and perform the activities in the manner, mode, and dose specified in the intervention theory and described in the intervention manual. Because clients also participate in the implementation of health interventions, the conceptualization of fidelity has been extended to clients’ enactment of the treatment recommendations, as intended or planned, in their daily life context (Prowse & Nagel, 2015).
Attendance to fidelity is increasingly emphasized in intervention evaluation (see Chapter 13) and implementation (see Chapter 16) research as a means to address var- iations in intervention delivery by providers and enactment by clients, which have been reported to contribute to outcome achievement (Roth & Pilling, 2008; Walton et al., 2017; Wang et al., 2015). Therefore, it is important to devise strategies to pro- mote fidelity of intervention delivery; to monitor fidelity regularly throughout the intervention delivery; and to assess and account for the influence of fidelity on the outcomes. Attendance to fidelity has several advantages in research and practice.
1. Promoting fidelity has the potential to reduce variations in intervention delivery by interventionists and health professionals. Providing the interven- tion as designed and consistently across clients enhances clients’ exposure to the content and activities required for their understanding and ability to carry out the treatment recommendations in daily life.
2. Monitoring fidelity with which interventionists and health professionals actu- ally deliver the intervention to clients shed light on:
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The providers’ ability and skills in applying the intervention’s components, conveying the content, and performing the activities as planned. Less‐than‐optimal performance of these skills identifies areas for further training (Lorencatto et al., 2013).
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The providers’ drift away from the intervention as designed at one point in time or over time (Kaye & Osteen, 2011): Monitoring provides an opportu- nity to observe drifts and to investigate reasons for the drifts. This information assists in early detection of error in delivery and suggests appropriate ways to address drifts, thereby preventing deviations from becoming widespread and long lasting (Borrelli, 2011).•
Challenges in providers’ delivery of the intervention and clients’ engage- ment and enactment of the intervention: Knowledge of these challenges helps to identify aspects of the intervention that require improvement and ways to revise the intervention (Bond et al., 2011; Di Rezze et al., 2013;Lorencatto et al., 2013; Prowse & Nagel, 2015).
3. Assessing fidelity and accounting for its influence on the outcomes generate empirical evidence to support the validity of inferences regarding the effec- tiveness of the intervention. Specifically:
a. Assessing the degree to which interventionists and health professionals delivered the intervention with fidelity helps to quantify the components actually given to clients. Comprehensive information on the specific and nonspecific components given and how these components, independently or combined, relate to levels of improvement in outcomes, is useful in determining which components contribute to outcomes. Differences in the association between components and outcomes across subgroups of the target population and/or context indicate the need for adapting the intervention. Similarly, assessment of the extent to which clients apply the treatment recommendations and examination of their contribution to outcomes generates evidence of the most relevant treatment recommen- dations for different client subgroups and in different contexts. Overall, this knowledge is useful for refining the intervention design, as needed (Wainer & Ingersoll, 2013), and revising the intervention manual; the revised manual identifies what adaptations can be made, how, for whom,
6.3 Intervention Fidelity
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in what context, without jeopardizing fidelity. Detailed descriptions of the adaptations inform the accurate replication of the intervention by differ- ent providers, with different clients, in different contexts (Campbell et al., 2013; Di Rezze et al., 2013; O’Shea et al., 2016; Toomey et al., 2019), which enhances external validity.
b. Empirical evidence on fidelity is critical for correct interpretation of the results obtained in intervention evaluation studies.
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When the results indicate that the intervention is effective in pro- ducing the hypothesized improvement in the outcomes, evidence on fidelity determines if the observed changes in outcomes are attribut- able to the intervention’s active ingredients represented in the appro- priate delivery of the respective specific components.•
When the results indicate that the intervention is ineffective, evidence on fidelity informs the investigation and identification of factors that may account for the findings.⚬ If the assessment of fidelity shows that the interventionists and health professionals deliver the intervention as planned, compe- tently and consistently, and that clients engage and enact the inter- vention as planned, yet the intervention did not produce the anticipated changes in the outcomes, then it can be validly con- cluded that the intervention as designed is ineffective.
⚬ If the assessment of fidelity demonstrates variations in the imple- mentation by interventionists and health professionals and clients, as well as in the levels of improvement in the outcomes, then it is clear that inappropriate delivery, rather than the intervention as designed, contributes to its ineffectiveness. Accordingly, evidence on fidelity avoids the commitment of type III error, that is, errone- ously inferring that the intervention is not effective when it is poorly implemented (Breitenstein et al., 2010; Rixon et al., 2016).
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The assessment of fidelity could also identify the extent to which con- tamination or dissemination of the intervention to the comparison treatment group occurred, that is, whether participants in the comparison group were exposed to any component of the intervention.Participants in the comparison group who are exposed to some inter- vention components experience improvement in the outcomes that may be comparable to the improvement reported by participants in the intervention group. This, in turn, reduces the size of the between‐
group differences in the outcomes and the power to detect significant intervention effects.
Overall, assessing and accounting for fidelity of intervention delivery in the out- come analysis provide the evidence to determine whether the outcomes are attribut- able, with confidence, to the intervention’s active ingredients, which is an issue of internal validity (e.g. Forsberg et al., 2015; O’Shea et al., 2016; Prowse & Nagel, 2015;
Stokes & Allor, 2016). Cumulating evidence supports a positive association between fidelity of delivery and outcomes observed following completion of interventions, implying that optimal implementation generates the hypothesized improvement in the outcomes (e.g. Bond et al., 2011; Dunst et al., 2013; Schwartz et al., 2018; Sundell et al., 2016; Wang et al., 2015).