Cristina A Godinho1, Maria-João Alvarez2, Maria Luísa Lima1, Ralf Schwarzer3,4. 1. a Instituto Universitário de Lisboa (ISCTE-IUL), CIS-IUL , Lisboa , Portugal. 2. b Faculdade de Psicologia , Universidade de Lisboa , Lisboa , Portugal. 3. c Institute for Positive Psychology and Education , Australian Catholic University , Sydney , Australia. 4. d Freie Universität Berlin , Berlin , Germany.
Abstract
OBJECTIVE: To examine the effectiveness of matching health messages promoting fruit and vegetable intake to the Health Action Process Approach stages of change. DESIGN: In a randomised controlled trial, 205 undergraduate students (non-intenders n = 123; intenders n = 82) were exposed to one of three health messages, targeted at non-intenders, intenders and controls. MAIN OUTCOME MEASURES: Three longitudinal assessments of stage, fruit and vegetable intake, and social-cognitive determinants were obtained. RESULTS: Stage-specific effects of the interventions were confirmed. For self-efficacy, a stage by health message crossover interaction emerged, with both non-intenders and intenders in the matched conditions scoring higher in self-efficacy. Furthermore, in line with predictions, non-intenders in the matched condition showed higher risk perception, outcome expectancies, intention, and stage progression immediately after message exposure, and lower levels of action planning and coping planning a week later in the mismatched condition, but for these outcomes no differences across conditions were obtained among intenders. Multiple mediation analyses confirmed the facilitating role of self-efficacy and behavioural intention among non-intenders. CONCLUSIONS: Stages should be considered when designing health messages, although more interactive interventions for intenders and extended measurement time frames may be required.
RCT Entities:
OBJECTIVE: To examine the effectiveness of matching health messages promoting fruit and vegetable intake to the Health Action Process Approach stages of change. DESIGN: In a randomised controlled trial, 205 undergraduate students (non-intenders n = 123; intenders n = 82) were exposed to one of three health messages, targeted at non-intenders, intenders and controls. MAIN OUTCOME MEASURES: Three longitudinal assessments of stage, fruit and vegetable intake, and social-cognitive determinants were obtained. RESULTS: Stage-specific effects of the interventions were confirmed. For self-efficacy, a stage by health message crossover interaction emerged, with both non-intenders and intenders in the matched conditions scoring higher in self-efficacy. Furthermore, in line with predictions, non-intenders in the matched condition showed higher risk perception, outcome expectancies, intention, and stage progression immediately after message exposure, and lower levels of action planning and coping planning a week later in the mismatched condition, but for these outcomes no differences across conditions were obtained among intenders. Multiple mediation analyses confirmed the facilitating role of self-efficacy and behavioural intention among non-intenders. CONCLUSIONS: Stages should be considered when designing health messages, although more interactive interventions for intenders and extended measurement time frames may be required.
Keywords:
fruit and vegetable intake; health message targeting; multiple mediation analyses; randomised controlled trial; stages of change