Exploring the cost-effectiveness of psychological therapies: analysis of a pilot Randomised Controlled Trial (RCT) of Acceptance and Commitment Therapy (ACT) for depression in the context of psychosis

Health, social, and economic burden related to schizophrenia is significant for both patients and wider society (Knapp, 2000; Chong et al., 2016). Depression is common in people with schizophrenia (Whitehead et al., 2002) and is associated with particularly high levels of health care use (Steel et al., 2015). Developing and disseminating cost-effective interventions for people with depression in the context of psychosis is therefore indicated. The ADAPT trial was a pilot randomised controlled trial (RCT) of Acceptance and Commitment Therapy for depression after psychosis (ACTdp) for individuals with a diagnosis of schizophrenia who also met diagnostic criteria for major depression (Gumley et al., 2015; Gumley et al., 2017). A total of 29 participants were randomised to ACTdp+ Standard Care (SC) (n=15) or SC alone (n=14). The aim of the present study was to explore outcomes relating to cost-effectiveness of ACTdp and to consider the feasibility of conducting an economic evaluation alongside a larger, definitive trial. Cost-effectiveness was explored in a cost-utility analysis (CUA) with quality-adjusted life years (QALYs) as the primary outcome. QALYs were calculated from the EuroQol (EQ-5D-5L) and cost data were collected using the Client Service Receipt Inventory (CSRI). The incremental cost-effectiveness ratio (ICER) for ACTdp was £8,339 which falls below the assumed threshold of £20,000 per incremental QALY used by NICE (2012). A trend towards better outcomes and partial cost-offsets in the ACTdp group suggests that ACTdp may be a cost-effective treatment and that a larger, definitive trial to explore this further would be justified