A pilot validation of a modified Illness Perceptions Questionnaire designed to predict response to cognitive therapy for psychosis

Abstract

Background and objectivesClinical 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.MethodsFifty-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.ResultsThe 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.LimitationsWe 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.ConclusionsThe Cure/Control subscale of the M-IPQ shows promise as a predictor of response to therapy. Specifically targeting these illness perceptions in the early stages of cognitive behavioural therapy may improve engagement and, consequently, outcomes.

Service user satisfaction with cognitive behavioural therapy for psychosis: Associations with therapy outcomes and perceptions of the therapist

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Thinking Well: A randomised controlled feasibility study of a new CBT therapy targeting reasoning biases in people with distressing persecutory delusional beliefs

“…Our previous proof-of-concept experiment suggested that working memory and negative symptoms moderated effects of the intervention on reasoning ( Garety et al., 2014 ). We also know that beliefs about the causes and treatability of one's problems and the relevance of psychological treatment may affect engagement, and consequently outcome ( Freeman, Dunn, Garety, et al, 2013 ; Marcus et al., 2014 ). An important goal of future research is to clarify the reasons for treatment engagement and treatment effect heterogeneity.…”

Confirming the structure of negative beliefs about psychosis and bipolar disorder: A confirmatory factor analysis study of the Personal Beliefs about Experience Questionnaire and Personal Beliefs about Illness Questionnaire

“…The Illness Perceptions Questionnaire (IPQ) has also been modified several times for use in those with psychosis (Lobban, Barrowclough, & Jones, ; Marcus et al ., ; Watson et al ., ). Although the modified IPQ shares some similar content with the PBIllQ and PBEQ, both considering causes and control over experiences, there are also some notable differences.…”