• Components of therapy as mechanisms of change in cognitive therapy for people at risk of psychosis: An analysis of the EDIE-2 trial

      Flach, Clare; French, Paul; Dunn, Graham; Fowler, David; Gumley, Andrew I.; Birchwood, Max; Stewart, Suzanne L. K.; Morrison, Anthony P.; University of Manchester ; Greater Manchester West NHS Foundation Trust/Liverpool University ; University of Manchester ; University of Sussex ; University of Glasgow ; University of Warwick ; University of Chester ; Greater Manchester West NHS Foundation Trust/University of Manchester (2015-05-21)
      Background: Research suggests that the way in which cognitive therapy is delivered is an important factor in determining outcomes. We test the hypotheses that the development of a shared problem list, use of case formulation, homework tasks and active intervention strategies will act as process variables. Methods: Presence of these components during therapy is taken from therapist notes. The direct and indirect effect of the intervention is estimated by an instrumental variable analysis. Results: A significant decrease in symptom score for case formulation (coefficient=-23, 95%CI -44 to -1.7, p=0.036) and homework (coefficient=-0.26, 95%CI -0.51 to -0.001, p=0.049) is found. Improvement with the inclusion of active change strategies is of borderline significance (coefficient= -0.23, 95%CI -0.47 to 0.005, p=0.056). Conclusions: There is a greater treatment effect if formulation and homework are involved in therapy. However, high correlation between components means that these may be indicators of overall treatment fidelity.