Trauma and posttraumatic stress disorder in Australia: Findings in the population sample of the Australian National Survey of Mental Health and Wellbeing

Aim: To investigate the distribution and risk factors for trauma and posttraumatic stress disorder in the Australian population sample taken for the 1997 National Survey of Mental Health and Wellbeing. Methods: The confidentialised unit record file (CURF) was prepared by the Australian Bureau of Statistics from the survey sample of 10 641 adults. It was interrogated for the lifetime experience of specific trauma and the 12-month prevalence of posttraumatic stress disorder according to DSM-IV and ICD-10. Univariate and multivariate analyses were applied to quantify risks for traumatic experience and for DSM-IV posttraumatic stress disorder. Results: Fifty-seven per cent of the population reported lifetime experience of the specified trauma. Men were more likely to experience most traumas and multiple traumas except for sexual assaults. The twelve-month prevalence of DSM-IV posttraumatic stress disorder in the overall adult population was 1.5%. It occurred in 3.8% of women and 2.0% of men who had experienced trauma. While female gender, youth, lower education and residence in poorer areas predicted posttraumatic stress disorder after trauma, multivariate analysis showed that the nature of trauma (especially sexual assault) predominated. Gender ceased to be a significant contributor to the risk of posttraumatic stress disorder when analysis controlled for type and number of trauma, and for the passage of time. Conclusion: Trauma is ubiquitous in the community and posttraumatic stress disorder is comparatively less common, persisting into the past year in 2.8% of those who have experienced lifetime trauma. The conventional models of female susceptibility to post-traumatic stress disorder are not supported in this sample. The type of trauma appears the most important determinant of progression to posttraumatic stress disorder. These community prevalence statistics complement causal understanding that comes from studies of clinical and other special populations in which posttraumatic stress disorder and selection for treatment may be confounded.