As we face the largest refugee crisis since World War Two, research is increasingly examining the impact of forced displacement. The risk of non-affective psychosis in refugees is evidenced to be significantly greater than non-refugees, and the role of pre-, peri- and post-migratory trauma and dissociation is increasingly implicated.
To determine the prevalence of non-affective psychosis in refugee populations.
PRISMA guidelines were followed. Three key databases (PubMed, PsychINFO and Web of Science), Google scholar and study references were searched. The full-text of 62 studies were screened and 23 studies were eligible for inclusion. A narrative synthesis was undertaken and the Quality Assessment Tool for Quantitative Studies was used to assess methodological quality. (PROSPERO registration CRD42019152170).
The results were widely heterogeneous. The combined weighted average prevalence of non-affective psychosis in refugee populations was 0.9 %. Psychosis prevalence for individual psychotic symptoms was 28.4 %; 0.5 % for schizophrenia; 1.0 % for psychosis; 0.6 % for mixed psychotic disorders and 2.9 % for psychotic episodes.
Variations in examined populations, diagnostic and prevalence classifications, and study designs and methodologies likely contributed to heterogeneity across the data. The findings highlight a greater need to provide more specialist mental health services and trauma-focused interventions, as well as transculturally sensitive assessment and treatment to address refugee vulnerability to psychosis. Future research should examine psychosis prevalence longitudinally and in refugees-only, address methodological bias and further examine the role of trauma and dissociation in refugee psychosis prevalence.

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