title: Predicting intention and behaviour following participation in a theory-based intervention to improve gluten free diet adherence in coeliac disease.
abstract: OBJECTIVE
  To determine whether changes in theory of planned behaviour (TPB) constructs could predict intention and gluten-free diet (GFD) adherence following participation in an online theory-based intervention designed to improve adherence in coeliac disease.
  
  
  METHODS
  Theory-based process evaluation of the mechanisms of change over the course of a six-week online intervention. Measures of GFD adherence and TPB variables were administered at baseline and follow-up (immediate post-intervention: n = 74; three-month: n = 68; six-month: n = 65). Hierarchical regression analyses using residualised change scores were conducted at each time point (dependent variables: intention and adherence).
  
  
  RESULTS
  Baseline intention and GFD adherence were the strongest predictors of follow-up intention and adherence, respectively. Change in attitude accounted for significant variance in intention. Change in intention accounted for significant variance in GFD adherence immediately post-intervention; by the six-month follow-up change in perceived behavioural control was the stronger predictor.
  
  
  CONCLUSIONS
  Partial support for the hypotheses suggests that, for certain behaviours, the TPB may be relevant in explaining the mechanism of action responsible for changes in intention and behaviour following participation in a behaviour change intervention. Additional predictive pathways are also likely to exist and, in the area of GFD adherence, may include habit strength and actual behavioural control.
authors.affiliation: a Behavioural Medicine Research Group, School of Psychology and Speech Pathology, Faculty of Health Sciences , Curtin University , Perth , Australia.
authors.forename: Kirby
authors.initials: K
authors.lastname: Sainsbury
authors.forename: Barbara
authors.initials: B
authors.lastname: Mullan
authors.forename: Louise
authors.initials: L
authors.lastname: Sharpe
mesh_terms: D002446:Celiac Disease / Q000178:diet therapy*; D055050:Diet, Gluten-Free / Q000523:psychology*; D005500:Follow-Up Studies; D006293:Health Promotion / Q000379:methods*; D006801:Humans; D033182:Intention; D020407:Internet; D010349:Patient Compliance / Q000523:psychology* / Q000706:statistics & numerical data; D011582:Psychological Theory; D012044:Regression Analysis
keywords: behaviour change; coeliac disease; gluten free diet adherence; intervention; theory of planned behaviour