[The epidemiology of post-traumatic stress disorders].

Post-traumatic stress disorder (PTSD) has been subjected to several epidemiological studies during the last 10 years. Large differences in prevalence between different studies can only partly be explained by differences in methodology, impact of the trauma and populations. Changes in diagnostic criteria, the stressor criteria, general mentality over time and cultural differences may account for some of the differences. In general populations a lifetime prevalence of PTSD of between 1% and 9% has been found. In unselected traumatized populations 20-45% will develop PTSD after exposure to significant traumas. Among soldiers who have participated in battles of war a PTSD prevalence of 15-20% has been found. After exposure to lesser traumas and among well-trained corps 5-10% develop PTSD. Over long periods the point prevalence of PTSD in a given traumatized population diminishes. Predictive factors related to PTSD are complex.