Assessment and monitoring of treatment fidelity in a multiple behaviour change intervention for smokers wishing to reduce but not quit.

Abstract

Background

Intervention fidelity considers the extent to which a behavioural intervention has been designed, delivered, and experienced as intended. The National Institute of Health’s Behaviour Change Consortium (NIH-BCC) provides a leading framework to examine fidelity across five domains: design, training, delivery, receipt, and enactment. This thesis presents a programme of research to develop methods for monitoring and assessing fidelity in multiple health behaviour change (MHBC) interventions across these five domains. Methods developed are presented and tested using data from a Trial of physical Activity assisted Reduction of Smoking (TARS), a multi-site NIHR-HTA funded MHBC intervention.
Methods

A mixed methods approach was adopted and comprised of five studies in which developed methods were tested. Study one assessed design fidelity through a qualitative assessment of the quality and coverage of the interventions underlying theory/core components as presented in an intervention manual. Study two assessed skill acquisition (one aspect of training fidelity) through semi-structured interviews with practitioners (n=7). Study three assessed the quality of delivery of the components of the intervention through an assessment of audio recorded delivery sessions (n=24) and semi-structured interviews with practitioners (n=8). Studies four and five assessed receipt and enactment fidelity, respectively, through semi-structured
interviews with intervention participants (n=8).

Results

Methods developed and presented here further our understanding of and approach to monitoring and assessing fidelity in MHBC interventions across the five NIH-BCC domains. All five domains need to be monitored and assessed in order to reflect the domain’s interdependency and interaction.
The utility of the developed methods were demonstrated through application to the TARS data and provided insight into the fidelity of TARS, for example, why and how physical activity was given less focus than smoking reduction within the delivery, receipt, and enactment domains.
Conclusions
Fidelity domains should be viewed as a dynamic, interdependent, and interactive processes that need to be assessed interdependently rather than as singular entities. Careful consideration of the timings for the monitoring and assessment of fidelity should be integrated into the design of intervention evaluation plans.

Date of Award	2025
Original language	English
Supervisor	Adrian Taylor (Director of Studies (First Supervisor)), Lynne Callaghan (Other Supervisor) & Tom Thompson (Other Supervisor)