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Table 2 Nine elements of intervention fidelity adapted from Hasson et al. [7]

From: Qualitative research to inform hypothesis testing for fidelity-based sub-group analysis in clinical trials: lessons learnt from the process evaluation of a multifaceted podiatry intervention for falls prevention

Element of implementation fidelity



Whether an intervention is being delivered as intended

Exposure or dose

Whether the amount of an intervention received by participants (frequency and duration) is intended

Quality of delivery

The way that those responsible for delivering the intervention deliver it

Participant responsiveness

How far participants respond to, or are engaged by, an intervention

Program differentiation

Identifying unique features of different components of programs and identifying which elements are essential

Intervention complexity

Complexity of an idea can act as a barrier to adoption - how complex is the intervention?

Facilitation strategies

When aiming to evaluate implementation fidelity, what are the specific strategies put in place to support implementation, e.g. provision of manuals, training and incentives. How were these strategies perceived by those involved in delivery?

• Recruitment

The recruitment strategies used to attract individuals to the intervention – what are the challenges to involvement?

• Context

What factors at political, economic, organisational and work group levels affected implementation?

  1. • Denotes new moderating factors for understanding fidelity