Participants
Participants have been surveyed as part of the German representative surveys of 2005 (REP 12), 2007 (REP 14), 2008 (REP 15a) and 2016 (REP 24). These are combined for analyzing the lifetime prevalence of traumatic events. Only the first three are used to establish the one-month-prevalence of PTSD as the corresponding items did not appear in REP 24. Participants have been chosen and data has been collected by a demographic consulting company (USUMA, Berlin, Germany) using a random-route procedure and random selection of a member of the identified households to assemble a representative sample. After providing informed consent, a total of 9,200 participants aged 14 to 93 (Nfemale = 4,987, Mage = 52.5, SDage = 18.4) answered the relevant questions, of which 6,693 participants (Nfemale = 3,635, Mage = 53.8, SDage = 18.5) took part in REPs 12, 14 and 15a, and 2,507 (Nfemale = 1,352, Mage = 49.21, SDage = 17.29) in REP 24. Further sociodemographic information can be seen in table 1. Ethical approval was granted by the institutional ethics review board of the University of Leipzig.
Measures
To determine whether participants live in West or East Germany, they were asked where they live at the moment. Participants who live in Berlin were assigned to east or west Berlin. Additionally, they were presented with the List of Traumatic Events screening instrument and the Posttraumatic Diagnostic Scale.
List of Traumatic Events
The trauma list of the Munich Composite International Diagnostic Interview [3] consists of eight potentially traumatizing events (e.g. “you were the victim of rape”, “… of a natural disaster”; “you had horrible experiences during war service”), and a question regarding the experience of “another terrible event or a catastrophe”. Two war-related items were added (“You were bombed”, “You were driven out of your homeland”). Participants responded in a dichotomous format (yes / no). Additionally, participants answered an item regarding the experience of intense fear and helplessness according to the DSM-IV A2 criterion of PTSD. If participants had experienced several potential traumata, they were prompted to indicate the subjectively most painful event, to which the following questions were then related.
Modified Posttraumatic Diagnostic Scale (German Version)
To screen for symptoms of PTSD, the German Version of the Posttraumatic Diagnostic Scale [19, 20] was used. However, the items corresponding to criteria B3, B4, C2, C3 and D2–D4 of the Diagnostic and Statistical Manual of Mental Disorder, version IV (DSM-IV) were omitted as Breslau et al. [21] have found these items to have low sensitivity and specificity and therefore be of low diagnostic value. The resulting scale includes 11 items regarding intrusions, avoidance and hyperarousal that were answered on a 4-point Likert scale ranging from 0 (“not at all) to 3 (“several times a week / almost always”). Items marked 0 or 1 (“once a week or less”) were counted as negative and those marked 2 (“2-4 times a week / half of the time”) or 3 were counted as positive. Additionally, the duration of the symptoms according to criterion E of DSM-IV has been screened. With a sensitivity of 80%, a specificity of 97%, a positive predictive value of 71% and a negative predictive value of 98% [21], the scale is well suited for screening for PTSD-symptoms.
To diagnose PTSD according to DSM-IV, items relating to criteria A1, A2 and four out of seven Symptoms relating to the B-criteria had to be marked as positive. Additionally, subclinical syndromes have been analyzed by specifying partial PTSD which has been diagnosed when at least two symptoms of criteria B to D are marked positive while the F-criterion is absent.
Statistical Analysis
All statistical analyses were run in the SPSS version 26. Descriptive stastistics were calculated separately for gender, place of residence, and three age cohorts. Three age cohorts were calculated for those born before 1947, born between 1948 and 1968, and after 1969. Additionally, chi-square tests were conducted to analyze possible differences between gender, former place of residence and age cohorts. One-month prevalence rates of full and partial PTSD were calculated for each group. To take recent developments in traumatic research into account these rates were analyzed for criteria A1 and A2 and only criterion A1 respectively.