Table 2 Factors influencing transferability

Indirect influence “dose intervention” factors

· whether the professionals followed the experimental protocol

· the group size

· the existence of incentives for the beneficiaries to facilitate and support their participation

· the training and coaching of participants in the protocol’s implementation

· the modifications for the new context

Direct influence “dose response factors”.

· category 1: Factors present in the target population that reduce the extent to which the intervention affects the outcome, defined as "antagonism."

· category 2: Factors present in the target population that enhance the extent to which the intervention affects the outcome, defined as "synergism".

· category 3: This category determines the beneficiaries’ actual need with respect to the intervention. This concept is based on the theory that the same dose will have less effect if there is less need for it and is defined as a "curvilinear dose–response association."

· category 4: The presence or absence of interventions that are antagonistic to the studied intervention, for example, the presence of messages dissonant to that conveyed by the intervention.

· category 5: The absence of a necessary cofactor in the causal chain of the intervention.

· category 6: The presence or absence of an external intervention that is synergistic with the objective of the intervention studied.