Prevalence and assessment of self-disorders in the schizophrenia spectrum: a systematic review and meta-analysis.

Self-disorders have been proposed as the "clinical core" of the schizophrenia spectrum. This has been explored in recent studies using self-disorder assessment tools. However, there are few systematic discussions of their quality and utility. Therefore, a literature search was performed on Medline, Embase, PsychINFO, PubMed and the Web of Science. Studies using these assessment tools to explore self-disorders within schizophrenia spectrum disorders (SSDs) were included. A meta-analysis was performed on the outcomes of total self-disorder score and odds ratios of self-disorders, using Comprehensive Meta-Analysis software. Weighted pooled effect sizes in Hedge's g were calculated using a random-effects model. 15 studies were included, giving a sample of 810 participants on the schizophrenia spectrum. Self-disorders showed a greater aggregation within schizophrenia spectrum groups compared to non-schizophrenia spectrum groups, as measured with the Bonn Scale for the Assessment of Basic Symptoms (Hedge's g = 0.774, p < 0.01) and Examination of Anomalous Self-Experiences (Hedge's g = 1.604, p < 0.01). Also, self-disorders had a greater likelihood of occurring within SSDs (odds ratio = 5.435, p < 0.01). These findings help to validate self-disorders as a core clinical feature of the broad schizophrenia spectrum.