21.8  Applicability and transferability

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).