Prevalence, predictors and associations of complex post-traumatic stress disorder with common mental disorders in refugees and forcibly displaced populations: a systematic review.

: The inclusion of complex post-traumatic stress disorder (CPTSD) in ICD-11 represents a turning point for the field of traumatic stress, with accumulative evidence of this disorder in refugees and displaced populations. : The objectives of this systematic review are to examine, in refugee and displaced populations: 1) the prevalence of CPTSD; 2) factors contributing to CPTSD; and 3) and associations between CPTSD and other common mental disorders including: PTSD, depression, anxiety and somatisation. : We followed the Joanna Briggs Institute Methodology for Systematic Reviews. Papers published in English language were included, with date of publication between 1987 and June 2019. We searched six relevant databases: MEDLINE, PsycINFO, Embase, Scopus, CINAHL, and PILOTS, and the grey literature. We included observational studies with prevalence data on CPTSD. : 19 articles met all inclusion criteria. Quality assessment was performed on each included study using the Joanna Briggs Institute Critical Appraisal Checklist for Studies Reporting Prevalence Data. Based on this, 13 moderate and high-quality studies were included in our narrative synthesis. The included studies reported prevalence of CPTSD in refugees and displaced populations ranging from 2% to 86%. : Reasons for the wide variation in prevalence may include contextual and geographical differences, the influence of post-migration difficulties, and sample population characteristics such as treatment seeking versus general population. We found higher prevalence rates (range: 16-82%) in more studies with treatment seeking samples, followed by convenience and snowball samples (40-51%), and lower rates in more studies utilising random sampling techniques (2-86%). Consistent with the broader literature, the studies in our review supported an association for complex post-traumatic stress disorder with prolonged, repeated trauma, and post-migration living difficulties, with the latter association being specific to refugee and displaced populations. Further research on this construct in this population group, including effective treatments, is required.