Applicability needs to be considered when deciding how to translate the findings of a given study or review to a specific population, intervention, or setting (see Chapter 12, Section 12.3). Transferability or the potential for translation are similar and appropriate terms. Applicability is closely related to integrity, context, and sustainability as discussed in previous sections of this chapter.
Systematic reviews of public health and health promotion interventions encompass several issues that make the process of determining applicability even more complex than in the clinical trials literature. First, a number of public health interventions do not involve randomization. Although not an inherent characteristic of non-randomized designs, these studies may have less well-defined eligibility criteria, settings, and interventions, making determinations of applicability more difficult. Then again, results from randomized trials may be less generalizable due to unrepresentative providers of the intervention or study participants not being typical of the target group (Black 1996). Second, public health and health promotion interventions tend to have multiple components. This makes it difficult to 1) determine what specific intervention component had the noted effect, and 2) assess the synergy between components. Third, in community interventions, implementation and adherence may be much more difficult to achieve and to measure. This also makes it harder to interpret and apply the findings. Fourth, in public health and health promotion interventions the underlying socio-cultural characteristics of communities are complex and difficult to measure. Thus it is difficult to define to whom and to what degree the intervention was applied, complicating determinations of applicability. On the other hand, this heterogeneity may increase applicability, as the original populations, settings, and interventions may be quite diverse, increasing the likelihood that the evidence can be applied broadly.
Review authors are ideally positioned to summarize the various aspects of the evidence that are relevant to potential users. This enables users to compare their situation or setting to that presented in the review and note the similarities and differences. Users can then be explicit about the relationship between the body of evidence and their specific situation.
The following questions may assist authors to consider issues of applicability and transferability relevant to public health and health promotion (Wang 2006).
Does the political environment of the local society allow this intervention to be implemented?
Is there any political barrier to implementing this intervention?
Would the general public and the targeted (sub) population accept this intervention? Does any aspect of the intervention go against local social norms? Is it ethically acceptable?
Can the contents of the intervention be tailored to suit the local culture?
Are the essential resources for implementing this intervention available in the local setting? (a list of essential resources may help to answer this question);
Does the target population in the local setting have a sufficient educational level to comprehend the contents of the intervention?
Which organization will be responsible for the provision of this intervention in the local setting?
Is there any possible barrier to implementing this intervention due to the structure of that organization?
Does the provider of the intervention in the local setting have the skill to deliver this intervention? If not, will training be available?
What is the baseline prevalence of the health problem of interest in the local setting? What us the difference in prevalence between the study setting and the local setting?
Are the characteristics of the target population comparable between the study setting and the local setting? With regard to the particular aspects that will be addressed in the intervention is it possible that the characteristics of the target population, such as ethnicity, socio-economic status, educational level etc, will have an impact on the effectiveness of the intervention?
Is the capacity to implement the intervention comparable between the study setting in such matters as political environment, social acceptability, resources, organizational structure and the skills of the local providers?