A systematic review of studies with a representative sample of refugees and asylum seekers living in the community for participation in mental health research

Background: The aim was to review the literature to identify the most effective methods for creating a representative sample of refugee and asylum seeker groups living in the community to participate in health and mental health survey research. Methods: A systematic search of academic and grey literature was conducted for relevant literature with 'hidden' groups published between January 1995 and January 2016. The main search used Medline, PsycINFO, EMBASE, CINAHL and SCOPUS electronic databases. Hidden groups were defined as refugees, asylum seekers, stateless persons or hard/difficult to reach populations. A supplementary grey literature search was conducted. Identified articles were rated according to a created graded system of 'level of evidence for a community representative sample' based on key study factors that indicated possible sources of selection bias. Articles were included if they were assessed as having medium or higher evidence for a representative sample. All full-text papers that met the eligibility criteria were examined in detail and relevant data extracted. Results: The searches identified a total of 20 publications for inclusion: 16 peer-reviewed publications and four highly relevant reports. Seventeen studies had sampled refugee and asylum seekers and three other hidden groups. The main search identified 12 (60.0%) and the grey search identified another eight (40.0%) articles. All 20 described sampling techniques for accessing hidden groups for participation in health-related research. Key design considerations were: an a priori aim to recruit a representative sample; a reliable sampling frame; recording of response rates; implementation of long recruitment periods; using multiple non-probability sampling methods; and, if possible, including a probability sampling component. Online social networking sites were used by one study. Engagement with the refugee and asylum seeker group was universally endorsed in the literature as necessary and a variety of additional efforts to do this were reported. Conclusions: The strategies for increasing the likelihood of a representative sample of this hidden group were identified and will assist researchers when doing future research with refugee groups. These findings encourage more rigorous reporting of future studies so that the representativeness of samples of these groups in research can be more readily assessed.