Cognitive Behavioural Therapy in Early Intervention for Psychosis: A Cost-Effectiveness Analysis

Background: Early intervention for psychosis (EIP) is a multidisciplinary ser- vice that treats individuals experiencing early psychosis. Treatment often consists of pharmacotherapy and cognitive behavioural therapy for psychosis (CBTp). While EIP demonstrates clinical efficacy and cost-effectiveness as a comprehensive package, the incremental contribution of its individual components remains unclear. With mental health services facing sustained funding pressures, understanding which EIP elements offer value for money is crucial for resource allocation decisions. Objectives: To evaluate whether CBTp used in conjunction with pharmacotherapy in EIP is cost-effective compared to pharmacotherapy alone. Methods: A cost-effectiveness analysis was conducted using a cohort-based Markov model from the societal perspective over a three-year time horizon. Model parameters were derived from a targeted literature review. The primary outcome was the in- cremental cost-effectiveness ratio (ICER), expressed as the cost per quality-adjusted life-year (QALY) gained. One-way sensitivity analysis (OWSA) identified influential parameters and probabilistic sensitivity analysis (PSA) quantified uncertainty around the ICER. Results: CBTp as an adjunct to pharmacotherapy resulted in a gain of 0.48 QALYs in the base case compared to pharmacotherapy alone. The corresponding ICER was £32,979 per QALY gained. This currently sits above the conventional up- per willingness-to-pay threshold of £30,000 per QALY. OWSA identified cost param- eters and utility parameters for symptom-free status as the most influential variables on the ICER. PSA showed that CBTp had approximately a 50% probability of being cost-effective at the £30,000 threshold. Discussion: Parameter uncertainty, particularly regarding costs and health utili- ties, drives the marginal cost-effectiveness case for CBTp. The intervention’s proximity to conventional thresholds suggests targeted improvements in service delivery or patient selection could enhance value. Conclusions: CBTp could potentially be a cost-effective adjunct to pharmacother- apy in EIP, however there is uncertainty around the results of this modelling. These findings support the targeted implementation of CBTp within EIP. Further high-quality long-term studies are recommended to strengthen the evidence base.