Cost-utility study of cognitive-behavioural management of auditory hallucinations in schizophrenia: a study protocol

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Abstract Background Auditory verbal hallucinations (AVHs) affect 60–80% of patients with schizophrenia, causing significant distress and functional impairment. Although cognitive-behavioural therapy (CBT) has been shown to reduce AVH-related distress and relapse risk, its use remains limited in many countries, including France, due to insufficient clinician training and time constraints. Consequently, treatment continues to rely mainly on second-generation antipsychotics, which have moderate efficacy and notable adverse effects. A structured CBT program combining Coping Strategy Enhancement, relational therapy, third-wave CBT, and imagery-focused techniques has the potential to further reduce the intensity of AVHs and associated distress. This study evaluates the clinical effectiveness and cost-utility of this intervention, with a view to its broader integration into psychiatric care. Methods This randomized controlled trial will assess the cost-utility and clinical effectiveness of CBT for AVHs in patients with schizophrenia spectrum disorders. A total of 240 patients, aged 15–60 years, experiencing distressing AVHs for at least three months, will be recruited from outpatient psychiatric services. Patients will be randomly assigned (1:1) to either the intervention group (CBT + treatment as usual, TAU), receiving 16 weekly one-hour individual CBT sessions in addition to standard care, or the control group (TAU alone), receiving standard psychiatric follow-up and pharmacological treatment without CBT. The primary outcome is the incremental cost-utility ratio at 12 months, expressed as cost per quality-adjusted life years (QALY) derived from the EuroQuality of life 5-dimension 5-Level questionnaire (EuroQol EQ-5D-5 L), comparing TAU alone with CBT + TAU. Secondary outcomes include changes from baseline at 4, 8, and 12 months in AVHs severity, depressive symptoms, suicidal ideation, quality of life, functioning, sleep quality, substance use, psychiatric comorbidity, pharmacological treatment exposure, and medication adherence. All endpoint assessments will be conducted by independent evaluators blinded to treatment allocation. Discussion This is the first large-scale medico-economic trial evaluating CBT for AVHs in France. Strengths include a randomized controlled design, stratification by illness severity, and blinded outcome assessment. By jointly assessing clinical efficacy and economic value, the findings could inform healthcare policy and support the implementation of CBT as a standard component of schizophrenia treatment. Trial registration Clinicaltrials.gov. Number: NCT07134816. Registered February 4, 2025.