BackgroundThe immense social upheaval and ongoing humanitarian crisis created by the 2011 war in Syria has forced millions of civilians to flee their homeland, many of whom seek refugee status in Western nations. Whilst it is known that the prevalence of mental illness is higher within refugee populations, this systematic review and meta-analysis aims to pool the prevalence rates of common mental disorders (namely posttraumatic stress disorder, depression and generalized anxiety disorder) in adult Syrian refugees resettled in high income Western countries.MethodsSeven electronic databases (Medline, PsychInfo, CINAHL, PTSDpubs, SCOPUS, PubMed and Embase) were searched up to the 31st of December 2020. Using pre-determined inclusion and exclusion criteria, relevant articles were screened by title and abstract, and later by full text. A meta-analysis was used to estimate the prevalence rates for each mental illness.ResultsEleven studies met the eligibility criteria for the systematic review. Nine of these studies had a low-moderate risk of bias and were included in the meta-analysis. Of the 4873 refugees included in the meta-analysis, the total pooled prevalence rate of having any of the three mental disorders was 33% (CI 95%, 27-40%), 40% for anxiety (CI 95%, 31-50%), 31% for depression (CI 95%, 20-44%) and 31% for PTSD (CI 95%, 22-41%). A meta-regression revealed that the total pooled prevalence rate for having any of the three mental disorders was not influenced by age, host country, duration in host country, educational or marital status.ConclusionsDespite significant study heterogeneity, the prevalence rates of common mental disorders in adult Syrian refugees resettled in high-income Western countries are significantly higher than reported rates in the general population.