Table 1 Conceptual framework for intervention fidelity used in this review

Content

Defined as an attempt to establish the ‘active ingredients’ of the intervention

Coverage

Refers to the degree to which all persons who met study inclusion criteria received the intervention

Frequency

Refers to whether the intervention was delivered with the regularity or frequency planned by its designers

Duration

Establishes whether the intervention was delivered with the duration planned by its designers

Comprehensiveness of intervention description

Factors such as the degree of intervention complexity and whether the intervention description is complete or incomplete, vague or clear, may influence the degree of intervention fidelity

Strategies to facilitate implementation

Several support strategies may be used to optimise and to standardise  intervention fidelity

Quality of delivery

Concerns whether an intervention is delivered in a way that increases the likelihood of achieving the desired health outcomes

Participant responsiveness

Refers to whether researchers established strategies to increase acceptance by and acceptability to those receiving an intervention

Recruitment^a

Refers to procedures used to attract potential programme participants

Context^a

Refers to surrounding social systems, such as structures and cultures of organisations and groups, and historical and concurrent activities and events, that may influence study activities