Theory informs the evaluation phases (Phase III—efficacy; and Phase IV— effectiveness) of an intervention somewhat differently than we have discussed thus far (Figure 4.1). At this stage of an intervention’s development, theory provides a basis for understanding the underlying mechanisms of action or how the intervention might result in positive outcomes. It also guides an understanding as to why and whether some groups or individuals may benefit from the intervention more than others (Gitlin et al., 2000).
More specifically, if an intervention is proven to be efficacious, then it is necessary to understand why and examine the pathways by which positive results have been achieved. Mediation and moderation analyses are typically the statistical approaches that are employed for these purposes. The specific hypotheses tested and variables selected for these analytic models must be informed by the theory or theories that underlie the intervention. As suggested earlier, the analyses in turn serve as a validation of the theory or theories and related hypotheses that frame the intervention. These analytic strategies help to examine the relationships among constructs and concepts of a theory and either verify, modify, refine, or refute them.
Figure 4.4 Use of behavioral change framework to guide delivery of an intervention.
In the earlier examples using the stress process models, one could evaluate whether an intervention reduces caregiver burden by mitigating an objective stressor such as the problem behaviors of persons with dementia. Similarly, one could test whether improving social support reduces burden. Mediation analyses could be used to test the independent and joint contributions of multiple mechanisms such as improving social support and reducing problem behaviors (Roth, Mittelman, Clay, Madan, & Haley, 2005).
The GBGB program was tested in an efficacy trial with 208 older African Americans. The Phase III trial demonstrated that the intervention group had reduced depressive symptoms and improved daily function and quality of life compared to a wait-list control group at 4 months. Furthermore, after receiving the intervention, the delayed treatment group similarly benefited (Gitlin et al., 2013). The social ecological model would suggest that multiple pathways were responsible for these outcomes. Behavioral activation theories would suggest that becoming behaviorally activated was the primary pathway in which depression reductions were achieved, although the other treatment components are necessary and support activation.
Mediation analyses confirmed that changes in depressive symptoms were achieved through multiple pathways and not exclusively through activation. The reduction of stress, the improvement of depression knowledge, use of selfmanagement techniques, and activation, all variables linked to the applied broad theoretical framework of the intervention (Figure 4.3), were jointly responsible for the significant reductions in depressive symptomatology. That is, activation was not the only mechanism by which depression was reduced (Gitlin, Roth, & Huang, 2014). These findings support the theoretical models and suggest that a condition for engaging in behavioral activation is that immediate environmental stressors must be addressed in concert with helping people achieve behavioral change. The findings also have important implications for GBGB’s translation and implementation into real-world settings. They suggest that all treatment components must be delivered in order to achieve positive benefits.
Furthermore, as the intervention was tailored to individual needs, differences in outcomes by demographic subgroups were not expected. This was shown to be the case through moderation analyses, which revealed that all participants benefited similarly as hypothesized; that is, men and women, those living alone or with others, and those with greater financial distress or without financial difficulties improved equally (Szanton, Thorpe, & Gitlin, 2014). This finding supports the notion that tailoring to the needs and personal behavioral goals of participants seems to be effective and an important delivery characteristic of this intervention.
To summarize, as the examples in this section demonstrate, theory at the evaluative phases can help guide selection of outcomes measures, explain mechanisms by which observed changes are achieved, and identify who may have benefited more or less and why.