Title: An explanatory randomised controlled trial testing the effects of targeting in treatment using cognitive behavioural therapy worry in patients with persistent persecutory delusions: The Worry Intervention Trial (WIT)
Funder: Department of Health (England)

Abstract: Background: Our approach to advancing the treatment of psychosis is to focus on key single symptoms and develop interventions that target the mechanisms that maintain them. In our theoretical research we have found worry to be an important factor in persecutory delusions. Worry brings implausible ideas to mind keeps them there and makes the experience distressing. Therefore we aim to test the clinical efficacy of a cognitive-behavioural intervention for worry for patients with persecutory delusions determine how the worry treatment might reduce delusions and develop the theoretical understanding of worry in psychosis. The project will produce a brief easily administered intervention that can be readily used in services. Research Design: An explanatory randomised controlled trial with 150 patients with persecutory delusions will be carried out. Patients will be randomised to the worry intervention in addition to standard care or to standard care. Randomisation will be carried out independently assessments carried out blind and therapy competence and adherence monitored. Two theoretical studies will be built into the baseline assessment. Population: Individuals with persecutory delusions and worry in the context of a schizophrenia spectrum diagnosis. They will not have responded adequately to previous treatment. Planned intervention: A 6 session cognitive-behavioural intervention will be presented on computer and assisted by a therapist. The control condition will be treatment as usual which is typically antipsychotic medication and regular appointments. Proposed Outcome Measures: The principal hypotheses are that a worry intervention will reduce levels of worry and that it will also reduce the persecutory delusions. The key outcome measures will therefore be the Penn State Worry Questionnaire and the Psychotic Symptoms Rating Scale – Delusions. Quality of life and service-user led reported outcomes will also be examined. Assessment and Follow-up: 0 weeks (baseline) 8 weeks (post treatment) and 24 weeks (follow up). Proposed Sample Size: The trial will run in two large NHS Trusts that cover a population of 2.4 million. In our randomised controlled pilot study the intervention led to a worry reduction of effect size 1.05 and a delusion reduction of effect size 1.35. We have conservatively powered the study to detect a lower effect size of 0.52. 150 patients are required (75 in each condition) allowing for 20% drop-out. Statistical Analysis: The statistical analysis strategy will follow the intention-to-treat principle and involve the use of linear mixed models to evaluate and estimate the relevant between- and within-subjects effects (allowing for the possibility of missing data). Both traditional regression and newer instrumental variables analyses will examine mediation. Timetables: The trial will take 2.5 years: 0-2 months training staff and setting up recruitment; 2-22 months recruitment intervention and assessments; 22-28 months final interventions and follow-ups; 28-30 months final data checking and analysis. The publication will be submitted within six months of the trial ending. The pilot recruitment rate was equivalent to 6 patients per month per full time researcher. We have therefore planned a recruitment rate of 4 patients per month per centre consistent with many of our other studies.


Research activity codes: 6.6 PSYCHOLOGICAL AND BEHAVIOURAL;5.6 PSYCHOLOGICAL AND BEHAVIOURAL
Health categories: MENTAL HEALTH