Risk and preventive factors of post-traumatic stress disorder (PTSD): alcohol consumption and intoxication prior to a traumatic event diminishes the relative risk to develop PTSD in response to that trauma.

Background: Previous reports examined the effects of selected pre- (e.g. female gender, previous trauma), peri- (e.g. the horror of the trauma, threatened death) or post-exposure (e.g. the physical injury caused by the trauma) risk factors on the development of post-traumatic stress disorder (PTSD), an anxiety disorder associated with a traumatic event outside the range of usual human experience. We hypothesized that alcohol consumption prior to traumatic events may reduce the incidence rate of PTSD. The aim of this study was to examine the effects of the above risk factors and preventive factors, such as alcohol consumption, on the development of PTSD. Methods: An epidemiological cohort study was carried out on 127 victims trapped in a ballroom fire. Data were collected, 7–9 months after the traumatic event, by means of the Composite International Diagnostic Interview (CIDI) and structured interviews, aimed to assess the above pre-, peri- and post-exposure factors. Logistic regression analysis was used to examine the association of PTSD with the etiologic factors and to delineate those risk factors which contribute most to the development of PTSD. Results: Female gender, the number of previous trauma, a past history of simple phobia, threatened death, trauma exposure, hospitalization for trauma-induced injuries and the presence of burns increased the odds of PTSD, whereas a sense of control during the trauma, and alcohol consumption and intoxication decreased the odds of PTSD. Six factors made independent contributions to the prediction of PTSD, i.e. the number of previous trauma, a past history of simple phobia, loss of control (increase the odds), a sense of control, alcohol consumption and alcohol intoxication (decrease the odds). Conclusions: The results of this study show that the development of PTSD is determined by the effects of pre-, peri- and post-exposure risk factors and may be prevented by the effects of peri-traumatic factors, such as sense of control, alcohol consumption and intoxication.