How and for whom are decision aids effective? Long-term psychological outcome of a randomized controlled trial in women with newly diagnosed breast cancer.

OBJECTIVE: The current study evaluates the long-term psychological impact of a decision aid intervention for surgical and systemic treatment in women with newly diagnosed breast cancer from a previous reported randomized, controlled trial (Vodermaier et al., 2009). METHODS: Patients (n = 111) were randomized into usual care, or a 20-min decision aid intervention plus an information brochure prior to consultation planning with the senior physician. The retention rate at 1 year was 88%. RESULTS: Linear mixed model analyses demonstrated that the intervention group experienced less decisional conflict (p = .047; d = .19), which was driven by perceptions of a more effective choice (p = .029; d = .20) over time. Subgroup analyses revealed that patients in the intervention group who participated in chemotherapy decision making showed better long-term body image outcomes (p = .009; d = .44), which were mediated by reduced depressive coping (p = .049). No effects emerged for anxiety and depressive symptoms, or for quality of life. Internal health locus of control moderated group effects on 'uncertainty with the decision' (p = .003). CONCLUSIONS: The study results provide novel evidence on the role of individual differences and the mechanisms behind decision aid effectiveness, and demonstrate the long-term impact of decision aid interventions on some indices of well-being.