Poster Presentation International Celiac Disease Symposium 2026

The Theory of Planned Behaviour Provides Important Insights into Behavioural Intentions to Participate in a Hypothetical Gluten-Challenge Trial (#325)

Amalia Marino 1 , Jesse Ekin 2 , Pragalathan Apputhurai 3 , Simon Knowles 3 , Jason A Tye-Din 4
  1. Medicine, Royal Melbourne Hospital, Parkville, VIC, Australia
  2. Gastroenterology, Royal Melbourne Hospital , Parkville, Victoria, Australia
  3. School of Health Sciences, Swinburne University of Technology, Melbourne, Victoria, Australia
  4. Tye-Din Lab, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia

Introduction

Understanding patient factors influencing clinical trial participation is increasingly important with the rise in development of novel therapies for coeliac disease (CeD). The Theory of Planned Behaviour (TPB) provides a framework for linking beliefs to behavioural intentions through attitudes, perceived social expectations and self-efficacy. This study examined how demographic factors, TPB constructs and additional psychosocial factors, including self-identity, altruism, moral norm, trial-related motivation and perceived barriers, influenced intentions to participate in a hypothetical CeD gluten-challenge trial.

 

Methods:

A total of 473 adults with diagnosed CeD completed the survey (mean age 50.4 years, 84.3% female, median time since diagnosis 14 years; 67.6% with a university or postgraduate qualification). Hierarchical multiple regression examined factors associated with intention to participate. The analysis first accounted for age, gender and education, then tested whether TPB constructs improved prediction of participation intention. Additional psychosocial factors were then added to determine whether they provided further explanatory value.

 

Results

After accounting for age, gender and education, the TPB variables explained 79.4% of the variance in intention to participate in a hypothetical gluten-challenge trial. Self-efficacy, reflecting participants’ confidence and perceived ability to take part, was the strongest predictor, β=.564, p<.001. Attitudes toward participation were also significant, β=.281, p<.001. Perceived social expectations, self-identity, altruism, moral norm, trial-related motivation and perceived barriers did not independently predict intention once self-efficacy and attitudes were considered.

 

Conclusion

Intention to participate in a hypothetical gluten-challenge trial was primarily associated with self-efficacy and attitudes. Recruitment should prioritise strengthening participant agency and self-efficacy, while fostering favourable attitudes through clear communication, flexible trial design and reassurance about symptom management. TPB offers a useful framework for participant-centred CeD trial design and recruitment.