Elena Marcus a , Philippa Garety a , John Weinman b , Richard Emsley c , Graham Dunn c , Paul Bebbington d , Daniel Freeman e , Elizabeth Kuipers a , David Fowler f , Amy Hardy a , Helen Waller a , Suzanne Jolley a , ∗
1 December 2014
Clinical responsiveness to cognitive behavioural therapy for psychosis (CBTp) varies. Recent research has demonstrated that illness perceptions predict active engagement in therapy, and, thereby, better outcomes. In this study, we aimed to investigate the psychometric properties of a modification of the Illness Perceptions Questionnaire (M-IPQ) designed to predict response following CBTp.
Fifty-six participants with persistent, distressing delusions completed the M-IPQ; forty before a brief CBT intervention targeting persecutory ideation and sixteen before and after a control condition. Additional predictors of outcome (delusional conviction, symptom severity and belief inflexibility) were assessed at baseline. Outcomes were assessed at baseline and at follow-up four to eight weeks later.
The M-IPQ comprised two factors measuring problem duration and therapy-specific perceptions of Cure/Control. Associated subscales, formed by summing the relevant items for each factor, were reliable in their structure. The Cure/Control subscale was also reliable over time; showed convergent validity with other predictors of outcome; predicted therapy outcomes; and differentially predicted treatment effects.
We measured outcome without an associated measure of engagement, in a small sample. Findings are consistent with hypothesis and existing research, but require replication in a larger, purposively recruited sample.
Illness beliefs predicted response to cognitive therapy in psychosis (CBTp).
Key predictors concerned the likelihood of curing or controlling problems.
The Cure/control subscale was expanded to include CBT-specific change items.
Findings could help to more efficiently target limited provision in routine services.
‘Pre-therapy’ interventions could target these beliefs to improve outcomes.