Informing the development of interventions aiming to increase participation in mail-out bowel cancer screening programmes

Informing the development of interventions aiming to increase participation in mail-out bowel cancer screening programmes

Background: Bowel cancer is the second leading cause of cancer-related death worldwide. Population mail-out faecal occult blood test (FOBT) screening, such as the Australian National Bowel Cancer Screening Program (NBCSP), is an effective way to increase the rates of early detection and thereby reduce bowel cancer mortality and the overall health burden associated with this disease. However, screening in these programmes is low and interventions aiming to increase participation rates have only had small to moderate effects. This thesis aimed to investigate ways in which interventions aiming to increase participation in mail-out FOBT screening programmes can be improved upon and better designed. Three studies using multiple research methods were conducted to achieve this aim.

Study one: The first study was a systematic review and meta-analysis. The review aimed to identify all interventions that promoted participation in mail-out bowel cancer screening programmes and explored if intervention effectiveness can be increased through targeting certain intervention types at specific subpopulations or by combining intervention types together. The review found 32 studies that met the inclusion criteria, these contained 30 trials that reported intervention effects within subpopulations and 17 trials that combined interventions. It was found that interventions rarely affect subpopulations differently, suggesting a targeting approach may not be effective, but combining interventions together generally led to larger increases in participation rates.

Study two: While findings suggest that a multifaceted intervention design approach should be taken, through reviewing the literature in study one it became evident that when designing multifaceted interventions, psychological and behaviour change theory was rarely considered, and it was unclear what the active components or underlying mechanisms responsible for the effectiveness of the interventions were. Therefore, study two implemented realist review methodologies to (a) use the behaviour change techniques (BCT) taxonomy v1 to identify the active components within each intervention, (b) use the accompanying theory and techniques tool to link each BCT with a theorised mechanism of action responsible for the behaviour change, and (c) apply a behaviour change model, the Health Action Process Approach (HAPA), to inform how BCTs can be combined to increase FOBT screening participation. Sixty-eight intervention trials were identified and analysed. Within these, 16 BCTs and 10 mechanisms of action were identified that successfully ii increased participation rates. Further, interventions that targeted both the motivational and volitional stage of the HAPA model were the most likely to be successful at increasing FOBT participation.

Study three: There has been limited research applying psychological theory to explain variation in FOBT screening participation or that explores invitee’s preferences for different intervention strategies. Study three involved the development and implementation of two scales designed for these purposes. First, the process approach to mail-out screening (PAMS) scale was developed to measure the constructs and process proposed by the HAPA model to explain the variation in FOBT screening behaviour. The user-ratings of mail-out screening interventions (UR-MSI) scale consisted of a series of example interventions based on the BCT taxonomy v1 to assess which intervention strategies were preferred by NBCSP invitees. The results of study three found that the HAPA model could explain half of the variation in FOBT screening participation and therefore should be used as a theoretical framework to base intervention design. The UR-MSI showed which intervention strategies had the highest endorsement rating within each factor of the HAPA model. This information can be used to create theory-based intervention strategies that are endorsed by the end-user.

Conclusion: The collective findings from this thesis provide a framework from which a multifaceted intervention can be constructed that makes the best use of the available evidence and psychological theory. Future interventions should take a multifaceted approach whereby several behaviour change strategies are implemented that target all motivational and volitional components of behaviour change specified in the HAPA model and BCTs should be selected that have high end-user endorsement to maximise participant engagement. In terms of increasing participation in the Australian NBCSP, motivational messaging in the initial invitation needs to be enhanced. The inclusion of general practitioners (GPs) in the invitation process, through GP endorsement letters, should be implemented. Further actions need to be taken to prevent invitees with high screening intentions from procrastinating and forgetting to participate.