A systematic review of adherence to group interventions in psychosis: do people attend?

Fifty-nine original research papers were included, reporting on 52 independent studies which consisted of 66 therapy groups comprised of 2109 participants. Average adherence was 76.4% (s.d. = 17.4). Adherence was improved by receiving incentives and was higher in participants of older age. Study sample size was inversely associated with adherence levels. Study quality was variable with approximately 61.5% found to be at risk of bias. The results support the feasibility of group therapy and suggest that adherence in people with psychosis is not dissimilar to those for people experiencing common mental health difficulties. These findings, alongside efficacy evidence, support the use of group interventions in people with psychosis but also highlight the need for further high-quality research on the efficacy for these approaches.