Abstract
Posttraumatic stress disorder (PTSD) is one of the most serious and incapacitating mental diseases that can result from trauma exposure. The exact prevalence of this disorder is not known as the literature provides very different results, ranging from 2.5% to 74%. The aim of this umbrella review is to provide an estimation of PTSD prevalence and to clarify whether the prevalence depends on the assessment methods applied (structured interview v. self-report questionnaire) and on the nature of the traumatic event (interpersonal v. not-interpersonal). A systematic search of major databases and additional sources (Google Scholar, EBSCO, Web of Science, PubMed, Galileo Discovery) was conducted. Fifty-nine reviews met the criteria of this umbrella review. Overall PTSD prevalence was 23.95% (95% confidence interval 95% CI 20.74-27.15), with no publication bias or significant small-study effects, but a high level of heterogeneity between meta-analyses. Sensitivities analyses revealed that these results do not change after removing meta-analysis also including data from underage participants (23.03%, 95% CI 18.58-27.48), nor after excluding meta-analysis of low quality (24.26%, 95% CI 20.46-28.06). Regarding the impact of diagnostic instruments on PTSD prevalence, the results revealed a lack of significant differences in PTSD prevalence when structured v. self-report instruments were applied (p = 0.0835). Finally, PTSD prevalence did not differ following event of intentional (25.42%, 95% CI 19.76-31.09) or not intentional (22.48%, 95% CI 17.22-27.73) nature (p = 0.4598). The present umbrella review establishes a robust foundation for future research and provides valuable insights on PTSD prevalence.